EP2719459A1 - Method and a device for controlling the pressure in a micro- or mesofluidic channel - Google Patents

Abstract

The method involves actuating a valve (10) for adjustment of a valve opening degree, and actuating a second valve (20) for adjustment of second valve opening degree. The actuation of one the valves is automatically carried out based on actuation of the other valve. A counter-coupling of driving parts of the valves is enabled, and a sum of flow resistances of the valves is kept constant. A preferably uninterrupted course of pressure in a micro-or meso fluidic channel (2) is set with positive and negative pressure values. An independent claim is also included for a device for controlling pressure in a micro- or a meso fluidic channel using a valve.

Description

The invention relates to a method and a device for controlling the pressure in a micro- or mesofluidic channel.

There is a microfluidic channel system according to the prior art WO 2004/103566 , The pressure is generated by a pressure divider system in which two valves are connected in series.

A disadvantage of the prior art is that there is a high gas consumption and a poor response of the pressure change to a change in a valve opening.

The object of the present invention is to improve the disadvantages of the prior art. In particular, the best possible control properties should be achieved.

The object is solved by the independent claims. Advantageous developments are defined in the subclaims.

• Ansteuern des ersten Ventils (10) bevorzugt zum Einstellen des ersten Ventilöffnungsgrades,
• Ansteuern des mindestens zweiten Ventils (20) bevorzugt zum Einstellen des mindestens zweiten Ventilöffnungsgrades,
  dadurch gekennzeichnet, dass
  das Ansteuern eines der Ventile (10, 20) automatisch und in Abhängigkeit von dem Ansteuern eines anderen der Ventile (10, 20) erfolgt.

In particular, the object is achieved by a method for controlling the pressure in a micro- or mesofluidic channel (2) by means of a first (10) and at least one second valve (20), wherein preferably the first valve (10) has a first adjustable valve opening degree and preferably the at least second valve (20) has at least a second adjustable valve opening degree, comprising the steps:

• Actuating the first valve (10), preferably for setting the first valve opening degree,
• Actuating the at least second valve (20), preferably for setting the at least second valve opening degree,
  characterized in that
  the control of one of the valves (10, 20) takes place automatically and in response to the activation of another of the valves (10, 20).

• Ansteuern des ersten Ventils (10) bevorzugt zum Einstellen des ersten Ventilöffnungsgrades,
• Ansteuern des mindestens zweiten Ventils (20) bevorzugt zum Einstellen des mindestens zweiten Ventilöffnungsgrades,
  dadurch gekennzeichnet, dass
  die Vorrichtung (1) weiterhin eingerichtet ist das Ansteuern eines der Ventile (10, 20) automatisch und in Abhängigkeit von dem Ansteuern eines anderen der Ventile (10, 20) durchzuführen.

The object is further achieved in particular by a device (1) for controlling the pressure in a micro- or mesofluidic channel (2) by means of a first (10) and at least one second valve (20), wherein preferably the first valve (10) has a first adjustable valve opening degree and preferably the at least second valve (20) has at least a second adjustable valve opening degree, wherein the device (1) is adapted for :

• Actuating the first valve (10), preferably for setting the first valve opening degree,
• Actuating the at least second valve (20), preferably for setting the at least second valve opening degree,
  characterized in that
  the device (1) is further set up to drive one of the valves (10, 20) automatically and in response to the activation of another of the valves (10, 20).

Due to the mutual dependence of the activation of the valves, these solutions make it possible to take into account and directly influence the pressure change dynamics and the flow to optimum values.

A micro- or mesofluidic channel is preferably a small container (micro: diameter / width of the container is less than 1 mm, meso: diameter / width is a few millimeters, about 1 to 10 mm), in which the pressure is reproducibly controlled and so reproducible movement and positioning of objects in the channel, e.g. B. of cells or molecules is possible. In the following, a mesofluidic channel or mesochannel is always understood as mentioned, even if only one microfluidic channel or microchannel is mentioned. Preferably, the fluid moves in the microchannel as, preferably exclusively, laminar flow.

The first valve and the second valve are preferably proportional valves, which are preferably controllable electrically or by pressure (air) and preferably by arithmetic unit. A pressure source (eg compressed air) may be connected or connected to the first valve, preferably a pressure sink (eg atmospheric pressure or a vacuum or a vacuum pump), preferably at least the pressure applied to the first valve higher than the pressure applied to the second valve. The first valve and the second valve are preferably connected in series by means of a line and form a pressure divider or a pressure divider system, similar to an electrical voltage divider with two resistors, wherein the microchannel between the valves via a fluid-related (pneumatic and / or hydraulic) connection is present. Preferably, more than two valves are present and these are preferably also connected in series and form a pressure divider with different points of attack for microchannels. More preferably, a plurality of pressure dividers from two or more valves are connected in parallel, so that at least two microchannels can be connected to the system of pressure dividers by means of a pressure source and sink. Preferably, the pressure divider formed by the valves operates with fluid, more preferably gas, more preferably with a liquid. In the following it is assumed in this regard, not restrictive manner of an operation with a gas.

The adjustable valve opening degree is preferably a value (greater than or equal to 0) for the adjustable opening state of the respective valve. The valve opening degree is preferably a percentage value in the range of 0% (valve closed) and 100% (valve completely open), particularly preferably the value of the surface area of the valve opening or a value functionally dependent on this surface area, particularly preferably in the case of round valve designs Radius r or preferably r ⁴ (Hagen-Poiseuille's law: volume flow - r ⁴ ) of the valve opening. The valve opening degree is preferably (strictly) monotonically dependent on the flow conductance G of the valve, where G = 1 / R and R is the flow resistance of the valve which the valve opposes to the fluid flowing through the valve. Preferably, the Strömungsleitwert G remains the same or is greater, the greater the valve opening degree. Preferably, the valve opening degree is preferably roughly the reciprocal of the flow resistance. Preferably, the valve opening degree eta corresponding flow resistance R of the valve is given by a characteristic f (eta) = R, z. B. known by the manufacturer. Preferably, the relationship between valve opening degree and flow resistance is linearized by taking into account the characteristic of the valve (control voltage or valve opening radius or valve opening area vs. flow resistance).

A control of a valve for setting a valve opening degree is preferably carried out by the application of an electrical or pneumatic control signal to the control input of the valve. Preferably there is a (preferably known or measurable) dependence between the control signal S and the valve opening degree eta via a characteristic curve g (S) = eta, more preferably between S and the flow resistance R over the characteristic curves f (g (S)) = R. Preferably, this dependence is proportional, particularly preferably linearly proportional, preferably due to performed characteristic linearization.

Preferably, according to the invention, driving the valve by means of a control signal and setting a valve opening degree and setting a flow resistance or flow conductance are considered to be equivalent within the scope of the invention, since these values relate only to characteristic curves which are known or measurable or can be estimated as an approximation and thus are considered.

The driving of one valve automatically and in response to the driving of another valve preferably means that a change in the valve opening degree of the one valve caused by driving automatically causes another driving causing a change in the valve opening degree of the other valve. One valve preferably serves as a master valve, another valve as a slave valve, which is automatically adapted to the valve opening degree of the master valve. This automatism does not necessarily result in any change in the valve opening degree of the master valve to a change in the valve opening degree of the slave valve. So leads the automatism z. Example, in a method according to the invention described below only to a change of the slave valve, when the master valve has a valve opening degree greater than a minimum valve opening degree, with the result that the minimum valve opening degree is set for the slave valve, so that the condition is met that the minimum valve opening degree is always set for at least one valve. In another method according to the invention, each change of the valve opening degree of the master valve preferably leads to a change of the valve opening degree of the slave valve. The automatism is particularly preferably reciprocal, so that the valve which z. B. is selectively controlled by a user and / or a control / control program, at least for this a current control to the master valve and the other valve is the slave valve. In this way, both the first valve depending on the situation master valve or slave valve and the at least second valve as well.

The dependence is preferably explicitly described as a formula S1 = F (S2) and / or S2 = F (S1), where F is an arbitrary function, S1 the size of the control signal for driving the first and S2 the size of the control signal for Driving the second valve is. Particularly preferably, the dependence is given as fuzzy logic, z. By defining a particular set of rules (closing one valve and / or opening the other valve if the pressure is too high, opening one valve and / or closing the other valve if the pressure is too low). In this way, although there is an independent definition of the control rules for each valve, these rules result in an implicit dependence of the valve states on each other. Preferably, the dependency is given only implicitly.

By controlling the valves is preferably the pressure in the microchannel, more preferably one or more variables such. The flow through the microchannel (or flow rate), the intensity of a fluorescence signal, the size or position of a gas bubble in the microchannel and / or nanoparticles and / or the deflection of elastic systems such as membranes or polymers, and gels, cells and / or cellular tissue regulated by feedback of the appropriate size. Preferably, the dependence of the control of the valves (in addition) is realized by means of the control loop.

In a further method according to the invention and in one embodiment of the device according to the invention, the dependence of the driving of one of the valves (10, 20) on the driving of another of the valves (10, 20) includes a counter coupling of the driving of the one of the valves (10, 20 ) and the driving of the other of the valves (10, 20).

In this way, the system to be controlled is linearized. Preferably, the pressure is regulated by means of PID or PD control (or PI or P control). Preferably, the target pressure is readjusted in small steps.

In a further method according to the invention and in one embodiment of the device according to the invention, the counter-coupling as a condition contains a constant holding the sum of a first flow resistance of the first valve (10) and a second flow resistance of the second valve (10).

Preferably, the sum of the flow resistance of the valves R = R1 + R2 is kept constant. In this method according to the invention, the valves are so coupled driven that the flow Q through the pressure divider constant remains. Thus, Q1 = Q2 = Q = const. (where Q1 is the flow through the first valve and Q2 is the flow through the second valve) and with Δp1 = R1 * Q, Δp2 = R2 * Q is Δp1 + Δp2 = (p1-p) + (p-p2) = p1 p2 = (R1 + R2) * Q (where p1 is the pressure of the pressure source applied to the first valve against atmospheric pressure, and p2> = p1 is analogous to the pressure of the pressure drop applied to the second valve; Δp1 is the one on the first valve and Δp2 on the second Valve decreasing pressure difference).

From this follows (p1-p) / R1 = (p-p2) / R2 = (p1-p2) / (R1 + R2) = const (where R1 and R2 represent the flow resistance of the first and second valve or conceivable the reciprocals of Valve opening degree, preferably as an approximation) and p1-p = const · R1 and thus p = p1-const · R1; and (p-p2) = R2 * (p1-p2) / (R1 + R2) and p = p2 + R2 * const.

By complying with the condition R1 + R2 = const. a change of the pressure occurs in linear dependence by a change of R1 (Δp = -ΔR1 · const) or R2 (Δp = ΔR2 · const). This allows a linear optimal control of the pressure (eg PD or PID with consistently optimal parameters over the entire pressure range.) In the prior art, this relationship is nonlinear (p (R1) = p1 * R2 / (R1 + R2) and thus Δp = (-p1.R2 / (R1 + R2) ² ) .DELTA.R1), which is why an optimal control would have to be non-linear there and thus, if at all, only very complicated to implement.

Preferably, by setting the flow Q as the operating point, the dynamics of the pressure increase and decrease are set. For this purpose, a low flow rate is preferably set via the sum R1 + R2, if a low gas consumption is required and the dynamics of the pressure increase and decrease is not the focus of the application. If higher gas consumption is acceptable and fast pressure rise and fall dynamics are required, a higher flow Q is set. A fast reaction dynamics requires a certain gas consumption, but no longer depends on the work area as in the prior art. Due to the dynamic reduction of the gas flow through the second valve at very high set pressure values, the gas consumption remains small. At low set pressure values, however, an almost closed first valve ensures minimum gas consumption.

Preferably, keeping the sum R1 + R2 constant is achieved by reverse coupling the setting of the first and second valve opening degrees. Prefers For this purpose, the sum of the reciprocals of the first and at least second valve opening degree eta1 or eta2 is kept constant. This corresponds to a rough approximation, namely valve opening degree eta ≅ G = 1 / R, but leads to an easy-to-implement coupling. Particularly preferably, R1 + R2 is kept constant by coupling the valve opening degrees and taking into account the valve characteristics R = f (eta) (valve opening degree → flow resistance), so that f1 (eta1) + f2 (eta2) = const. and thus
eta1 = f1 ^-1 (const.-f2 (eta2)) or eta2 = f2 ^-1 (const.-f1 (eta1)), especially with additional consideration of the valve characteristics eta = g (S) (control signal -> valve opening degree).

In a further method according to the invention, a first minimum valve opening degree is defined or defined for the first valve (10) and an at least second minimum valve opening degree is defined or defined for the at least second valve (20) and the dependence of the activation of the one of the valves ( 10, 20) of the driving of another of the valves (10, 20) includes the condition that is always set for at least one of the valves (10, 20) of the respective minimum valve opening degree by the driving of the valves (10, 20). In one embodiment of the device according to the invention, such minimum valve opening degrees are defined or definable, and the dependence of the driving of one of the valves (10, 20) on the driving of another of the valves (10, 20) also includes this condition.

In this way, a valve is always kept in the state of its minimum valve opening degree, whereby the gas consumption is considerably reduced, in particular when the minimum valve opening degree corresponds to a completely tight closing position of the valve. This condition is preferably established by means of an analog or logic circuit or a computer program by means of Boolean arithmetic.

For example, the first valve is opened only when the second valve is closed and the second valve is opened only when the first valve is closed.

The minimum valve opening degree is preferably set automatically by means of a program or specific setting means (eg rotary knobs). Preferably, the minimum valve opening degree is different from the completely sealed closure position of the valve. This is particularly advantageous if the microchannel is subject to leakage, since the thus displaced zero opening of the respective valve compensates for the loss due to this leak, or if the function of the valve is not ensured for a very small opening. Preferably, the lost gas is replaced again by the first valve does not close completely after the pressure pulse, but only so far that the loss is compensated. Preferably, the minimum valve opening degree is used for this purpose as a control variable of a pressure control, which compensates the pressure loss due to possible leaks and / or ensures a minimum gas flow through a valve (eg a PID, P, CW PID control, CW: continuous wave, ie continuous control signals, or PWM-PID, PWM: pulse width modulation, ie additionally or alternatively, the manipulated variable of the control is the pulse duration of control pulses). Instead of a PID element, a P, PI or PD element is also conceivable (this applies to the entire application).

Also, a minimum valve opening degree, which is a residual opening of the valve, is advantageous if the system has a gas reflux (eg vacuum sink or receiver) and thus forms a closed circuit. So the gas is constantly returned to the sink, which z. B. is advantageous in toxic or radioactive gases. Thus, not only gas losses in the system can be compensated, but also a precise and permanent perfusion can be achieved.

In a further method according to the invention, the activation of the first valve (10) and the activation of the at least second valve (20) set a preferably uninterrupted course of the pressure in the micro- or mesofluidic channel (2) with positive and negative pressure values. In one embodiment of the device according to the invention, the latter is set up to carry out such a control of the first valve (10) and such a control of the at least second valve (20).

Positive and negative pressure values preferably relate to the atmospheric pressure, which corresponds to the pressure value 0.

By applying pressure and vacuum, liquids and their objects in the micro- or mesofluidic channel can be positioned more flexibly, much faster and more precisely than just with pressure.

In a further method according to the invention, at least one of the valves (10, 20) is controlled in the form of at least one pulse for generating at least one pressure pulse in the micro- or mesofluidic channel (2). In one embodiment of the device according to the invention, this is set up to perform such a drive.

The pulse preferably has an arbitrary pulse shape, more preferably it is a rectangular or trapezoidal pulse. It preferably has a pulse duration and a pulse height and / or a pulse curve integral value. The pulse curve integral value is preferably a value of the area integral of the area below the pulse curve, preferably with the integration limits t0 (pulse start) and t1 (pulse end). Preferably, the gas volume moved by means of a pulse and preferably the pressure built up thereby is determined by the integral via the pulse curve.

The pulse height or pulse amplitude for the valve actuated by the pulse preferably represents a value which is proportional to the valve opening degree set by the actuation (preferably without consideration of system inertia), preferably the product valve opening degree · opening time. Preferably, the device for driving electrical control signals to the valve, which have the pulse-shaped course. Preferably, with the activation of a valve in the form of a pulse (control pulse), a pressure pulse or a pressure change in the microchannel is established, which is proportional to the pulse curve integral.

Preferably, both valves are controlled with at least one pulse, particularly preferably with a sequence of pulses. Preferably, the gas consumption and the dynamics of the pressure increases and / or waste are optimized for the control of the two valves. Preferably, the valves are exclusively controlled. The application of a rectangular pressure pulse with maximum opening is the fastest possible method of adjusting the actual pressure to the target pressure. Since the respective other valve is preferably closed or in the state of the minimum valve opening degree, the gas flow is minimal. If the channel volume in the system, in the experiment and in the supply lines is minimal, a maximum response with minimum gas consumption is possible. Pulses of high amplitude and small opening duration are used to achieve a fast control dynamics or reaction speed. Pulse Small amplitude and long opening time are used to achieve a low control noise and / or to achieve a slow control dynamics.

In a further method according to the invention, the number of gas particles displaced with one of the generated pressure pulses in the micro- or mesofluidic channel (2) is determined and / or the volume displaced by one of the generated pressure pulses in the micro- or mesofluidic channel is determined and / or the internal volume of the micro or mesofluidic channel (2) is determined. In one embodiment of the device according to the invention, this device is set up to determine these parameters.

In this way, with knowledge of one or more of these system parameters, a predictive calculation of a control can be carried out. So z. B. the shape (height, duration) of a control pulse for a required pressure effect previously calculated. Thus, an exact rules possible. For example, ultrashort and small pulses allow for the smallest corrections of the position of nanoparticles, molecules, or cells in microchannels, for example. The pulse duration and amplitude of a control pulse and / or pressure pulse are preferably calculated on the basis of a model of the valve and preferably of the system. Preferably, small remaining deviations between desired value and actual value, which still result after the execution of such a calculated control pulse and / or pressure pulse, are corrected by PID control or again by a predictively calculated control pulse and / or pressure pulse. Preferably, the first and / or second minimum valve opening degree is regulated by means of predictive control.

Preference is given to a rectangular or trapezoidal pressure pulse, which occurs in response to a control of a valve in the form of a rectangular or trapezoidal pulse, with knowledge of the set valve opening (the maximum opening is suitable, since it is specified by the manufacturer, for example ) the volume flow is calculated for a given pressure difference. The calculation of the volume flow ΔQ [m ³ / s] is preferably carried out according to ΔQ = ΔP / R, where ΔP is a given pressure difference and R is the flow resistance dependent on the valve opening.

Preferably, the temperature T of the gas in the pressure divider system is measured directly or indirectly. Preferably, this is done by a control pulse

Pressure increase Δp measured in the pressure divider system. Preferably, with the temperature of the gas, the pressure increase in the pressure divider system and knowledge of the internal volume V, the number of inflowed / shifted gas particles ΔN = Δp * V / (k * T) is calculated, where k is the Boltzmann constant. The change of the gas volume ΔV in the microchannel is preferably calculated on the basis of the inflowing gas particles ΔN according to the following relationship: ΔN = (ΔV × rho × Na) / M, where rho is the density of the gas [kg / m ³ ], Na is the Avogadro number [1 / mol] and M is the molar mass of the gas [kg / mol]. This allows the realization of stoichiometric chemical reactions between gases or gases and liquids or between liquids or liquids / gases and solids in microchannels.

Preferably, both valves are closed and by an induced change in the temperature in the microchannel, the internal volume is determined by measuring the resulting pressure increase Δp: V = N · k · ΔT / Δp.

Alternatively or additionally, the internal volume V is determined by opening the second valve connected to the pressure sink, preferably to the atmosphere, preferably completely or to a certain degree for a given time interval (while the other valve is closed) and meanwhile the exponent of Pressure drop curve is measured (the valve opening must be known, eg by the manufacturer). The excess of gas particles then displaces the volume V = N · k · T / Δp in the microchannel system after opening the valve connected to the pressure sink. The internal volume V is calculated by measuring the relaxation time tau = R * C according to the formula V = tau * Na * rho * k * T / (R2 * M).

By knowing the pressure and the system volume, the expansion volume is preferably determined when opening the outlet valve. The relative volume change ΔV / V due to a pressure change Δp is ΔV / V = M / (Na · rho · k · T) · Δp; where M is the mean molar mass of the fluid (preferably air = 28.9 g / mol), Na the avogadro constant, rho the density of the fluid, k the Boltzmann constant and T the temperature.

The pneumatic capacitance C (tau = C * R2) is preferably determined by means of at least one calibration pulse and the measurement of the pressure response, in particular the decay constant tau, if the resistance R2 of the output valve is known (see data sheet of the manufacturer). It is also possible to dew over the Relaxation time for a given pressure change Δp to be determined tau = Δt / In (Δp / p_sys). Furthermore, the following relationships apply to square-wave pulses ΔV = Q · Δt = C · Δp, where Q is the volume flow and ΔV is the gas volume flowing in or out and Δt is the pulse length. The ideal gas equation independently establishes a relationship between pressure change and gas particle number: Δp = ΔN · k · T / V which, with the aid of the density rho and the molar mass M, yields a second relationship between pressure difference and volume difference: ΔV = V · M / (Na · rho · kT) · Ap. The pneumatic capacity C is thus preferably determined by means of C = V × M / (Na × rho × k × T). This value is preferably redetermined during system calibration, preferably for each arrangement. Because the inner volume V changes depending on the volume of the connected micro-channel system including the supply hoses.

Again, this method allows in the simplest way the best possible optimization of the control parameters.

The control of the valves in the form of at least one pulse thus allows, together with knowledge of the temperature, a complete characterization of all system parameters of the microchannel system: internal volume, number of additional gas particles after a pressure pulse and the corresponding displacement volume. Preferably, the system parameters R1 · V and R2 · V are determined.

In a further inventive method , the at least one pulse has a long pulse duration and / or a high pulse height and / or a large pulse curve integral value for coarse positioning of objects and / or fluids in the micro- or mesofluidic channel (2) and the at least one pulse has a shorter pulse duration and / or a lower pulse height and / or a small pulse curve integral value for fine positioning. In one embodiment of the device according to the invention, this device is set up to set such pulse durations and pulse heights and / or pulse curve integral values for the at least one pulse.

In this way it is exploited that proportional valves can generate gas pulses both by a short opening with a large amplitude or pulse height or by a longer opening with a small amplitude. This control is preferably triggered manually or automatically, z. B. at the same time microscopic Observation by an experimenter and / or with a camera, preferably with image processing and / or other measuring systems. Large pressure surges with high pulse height and / or long pulse duration and / or a large pulse curve integral value are triggered for rapid positioning of the objects in the microchannel, while smallest movements, eg. B. after coarse positioning, by gas packets smaller amplitude and / or short pulse duration and / or small Pulskurvenintegralwert be performed.

In a further method according to the invention, a measured variable in the micro- or mesofluidic channel (2), in particular the pressure, is regulated to a desired value by repeated actuation of the valves (10, 20) in the form of the at least one pulse. In one embodiment of the device according to the invention this is set up to regulate according to a desired value.

A measured variable is z. The pressure in the microchannel, the flow through the microchannel, the intensity of a fluorescence signal, the size or position of a gas bubble in the microchannel and / or nanoparticles and / or the deflection of elastic systems such as membranes or polymers, as well as gels, cells and / or cellular tissues.

Preferably, the control noise is set by the choice of the amplitude or pulse height and / or pulse duration, wherein short high pulses lead to a larger noise of the regulated pressure than long low pulses. For this purpose, high-amplitude pulses allow a maximum possible adaptation of the pressure, and preferably a faster adaptation. This is partly analogous to quantum mechanics: a certain amount of energy can be transmitted by a few high-energy or many low-energy photons. The noise of the energy of the photons is limited by the Heisenberg uncertainty relationship ΔE · Δt> h / (4 · π) (where h is the Planckian effect quantum). The energy fluctuation ΔE is large when the length (= duration · light velocity) of the wave packets is small for the quantum condition to be satisfied. If you want to achieve small noise, it is advantageous to use many low-energy photons. This illustrates impressively that also a modulation of the pulse amplitude with proportional valves is important to control the pressure.

Preferably, the control is carried out with the secondary condition that there is always at least one valve in the state of the minimum valve opening degree. Particularly preferably, the valves are therefore only open alternatively, as long as the minimum valve opening degree corresponds to the closed position.

Preferably, the regulation of the pressure is carried out by repeated actuation of the valves in the form of the at least one pulse with simultaneous measurement of the actual pressure. Preferably, the valves are driven alternately with pulses. The pulse duration and / or the pulse height and / or the value of the integral are preferably controlled via the pulse curve as a function of the deviation between the actual and setpoint pressures. In this case, the minimum pulse duration of a pulse is preferably greater than or equal to the response time of the actuated valve (eg greater than or equal to 1 μs, preferably greater than or equal to 250 μs, preferably greater than or equal to 500 μs), preferably at least when the control for this pulse a pulse height or a pulse integral of more than 0 is calculated. Because the minimum pulse duration is preferably greater than the response time of the controlled valve, it is ensured that the valve is opened and closed in accordance with the pulse progression and that the valve is not opened and closed as in classical PWM following a mean value of the pulse progression Mean value would be due to the valve inertia. Thus, maximum steep pressure pulse edges are generated. Preferably, an amplitude is selected in advance and the regulation takes place over the pulse duration. It is also conceivable that the pulse duration is selected in advance and the pulse height is used as a control variable for the regulation of the pressure. The pulse height required for pressure control as a manipulated variable is set, for example, by means of a CW-PID control (continuous PID control).

Preferably, CW-PID minimizes the pulse height, which preferably results in maximum pulse broadening. Finally, the pulses preferably pass into continuous analogue opening values of the two valves, which are regulated by PID.

An exemplary control method consists in preferably opening the valve connected to the pressure source at a pressure p_act <p_setpoint (p_act: measured pressure in the microchannel, p_setpoint: setpoint pressure in the microchannel), preferably to at least 60%, preferably at least 85%, particularly preferably at least 95% or even 100% of the target pressure reached. At p_ist> p_soll is correspondingly the valve connected to the pressure sink, preferably maximally opened, preferably to p_ist equal to or less than 140%, preferably equal to or less than 115%, more preferably equal to or less than 105% of the target pressure reached. Thus, in the event of a deviation from the setpoint pressure, the respective corresponding valve is actuated to correct the actual pressure, the condition implicitly also being realized that at least one of the two valves is in the state of the minimum valve opening degree. Preferably, the respective valve opening degree is then reduced and the pressure achieved is preferably further approximated by smaller corrective pressure pulses (or corresponding control in the form of pulses) the target pressure and / or kept constant. Preferably, the valve connected to the pressure source is kept completely closed as long as no pressure increase is required. Preferably, the valve connected to the pressure sink is kept completely closed as long as no pressure reduction is required. This is particularly advantageous in non-leaking gas saving systems. Particularly preferably, the valve connected to the pressure source then remains slightly open in order to maintain the desired pressure, which is advantageous in the case of systems subject to leaks in order to compensate for gas leakage through leaks without having to constantly readjust. Preferably, the method of pulse control by prolonging the pulse durations to long, constant pulses (which in between no longer significantly close and far a valve) in the initially described inventive method with a negative feedback or in a method of the prior art without negative feedback, z , B. with a first valve, the valve opening degree is controlled and a second valve, which is constantly opened by a certain degree transferred.

By reducing the valve opening degree after approaching the setpoint, and preferably by the smaller amplitude corrective pressure pulses, the control noise is reduced. The adjustment of the amplitude of the pulses is preferably controlled by a PID algorithm. Preferably, the actual value is recursively approximated to the desired value.

Preferably, a mixture of a control by means of the pulse duration as a control variable and a control by means of the pulse height is performed as a manipulated variable (eg., Via a cascade control). For the compensation of large differences between the actual and setpoint pressure, a control is carried out by means of pulses with a fixed pulse height, being controlled as the manipulated variable over the pulse duration. This uses the better dynamics of pulses with high pulse amplitude. For the fine control with small differences between actual and nominal pressure, a pulse height modulation is preferably carried out. Thus, the pulses become relatively wider and lower and the control noise decreases.

Preferably, the control dynamics are freely selectable, more preferably it is automatically adjusted. If a desired pressure change is desired, a control with a large, preferably maximum amplitude is made, whereas when a target pressure is kept constant, a small amplitude is used. More preferably, an automated sliding transition is performed by first selecting the maximum valve opening degree for a pulse after a target pressure change, and then decreasing the pulse amplitude by decreasing the valve opening degree for subsequent pulses, e.g. For example, an exponential decay is given by the formula: A (t) = amine + (amax-amine) x exp (-t / theta) where A is the valve opening degree, amine is the minimum and Amax is the maximum valve opening degree, and theta is the transition time constant.

In a further inventive method is controlled by means of a control and a reaction speed and / or a control noise of the control is chosen freely and / or adapted by an algorithm to application requirements. In one embodiment of the device according to the invention, this device is set up to regulate by means of a control and a control noise of the control is freely selectable and / or adaptable to application requirements by an algorithm.

The control noise is preferably due to the reaction rate. Preferably, the higher the reaction rate, the higher the control noise.

In a further method according to the invention, the pulse duration and the pulse height and / or the pulse curve integral value are determined as a function of a change in the pressure to be achieved in the microfluidic or mesofluidic channel (2). In one embodiment of the device according to the invention, this device is set up in such a way to determine the pulse duration and the pulse height and / or the pulse curve integral value.

The change in the pressure to be achieved is preferably the difference between the measured actual pressure and the desired pressure. Preferably, a predictive calculation of the valve opening (or pulse height) and opening time is performed, whereby the PID control of the pulse amplitudes or widths is preferably no longer required.

• Anstieg (Ventil 1 offen, Ventil 2 geschlossen): p(t)/p1 = 1 - exp(-t/(R1·C))
• Der Systemdruck beträgt dann nach einer Offnungzeit Δt: p_sys/p1 = 1-exp(-Δt/(R1·C))
• Abfall (Ventil 2 offen, Ventil 1 geschlossen) für eine Zeit (z. B. für die Zeit bis der Druck sich halbiert hat p(Δt_0,5)=0,5·p_sys): p(t) = p_sys·exp(-t/(R2·C)).

The prediction is preferably carried out by the following prescriptions for the pressure curve, wherein preferably the initial pressure is equal to the atmospheric pressure:

• Rise (valve 1 open, valve 2 closed): p (t) / p1 = 1-exp (-t / (R1 * C))
• The system pressure is then after an opening time Δt: p_sys / p1 = 1-exp (-Δt / (R1 · C))
• Drop (valve 2 open, valve 1 closed) for a time (eg, for the time until the pressure has halved p (Δt_0.5) = 0.5 * p_sys): p (t) = p_sys * exp ( -t / (R2 · C)).

Preferably, when lowering the pressure by opening the second valve, a certain pressure is waited, z. Until half the pressure has been set: p (Δt_0.5) / p_sys = 0.5. From this, the relaxation time R2 · C = Δt_0.5 / ln (2) is obtained. This measurement is preferably performed repeatedly and times are averaged to increase accuracy.

R · C is the combination of flow resistance in the system R = p / Q and C, which depends on the internal volume V and the temperature T: Δp = C · ΔV. The volume flow is Q = dV / dt.

• Für eine Druckerhöhung (Öffnung des Eingangsventils) gilt zunächst folgende Formel: p(t) = p1-(p1-p_sys)-exp(-t/(R1·C))
• Für eine Drucksenkung (Öffnung des Ausgangsventils) gilt zunächst folgende Formel: p(t) = p2-(p2-p_sys)·exp(-U(R2·C))
• Dabei ist p1>=p2. Die Zeiten und Amplituden ergeben sich dann aus folgenden Zusammenhängen (*):
  für den Anstieg: In((p1-p_sys)/(p1-p_soll)) = Δt/(R1·C) (= xi1),
  für den Abfall: In((p_sys-p2)/(p_soll-p2)) = Δt/(R2·C) (= xi2).

The precalculation of the pulse height and pulse duration for a required pressure change requires knowledge of the parameters R1 * C and R2 * C. The determination is made as follows. With knowledge of the inlet pressure, the resistances of the fully opened valves and the system volume and the current system pressure p_sys, the opening time and amplitude are determined as follows:

• For an increase in pressure (opening of the inlet valve), the following formula initially applies: p (t) = p1- (p1-p_sys) -exp (-t / (R1 * C))
• For a pressure reduction (opening of the outlet valve), the following formula initially applies: p (t) = p2- (p2-p_sys) * exp (-U (R2 · C))
• Where p1> = p2. The times and amplitudes result from the following relationships (*):
  for the slope: In ((p1-p_sys) / (p1-p_set)) = Δt / (R1 * C) (= xi1),
  for the decay: In ((p_sys-p2) / (p_soll-p2)) = Δt / (R2 · C) (= xi2).

These relationships predict values of a time / amplitude combination needed for a given pressure change. By preselecting the amplitude or preselecting the pulse duration, first the control dynamics and the noise are set. With a high amplitude or a short pulse duration, faster dynamics with higher control noise are set, while with a low amplitude or long pulse duration, a slower dynamic with lower control noise is set. The then missing parameter of the pulse (pulse duration or amplitude) is calculated via the above-mentioned relationships.

In order to convert the resistance value R1 or R2 into an amplitude, the characteristic curve R1 = f1 (eta1) or R2 = f2 (eta2) (x-axis: amplitude or value of the valve opening degree, y-axis: flow resistance) and / or the characteristic curve R1 = f1 (g1 (S1)) or R2 = f2 (g2 (S2)) (x-axis: amplitude or value of the control signal, y-axis: flow resistance) used by the manufacturer, eg. B. this is programmed into the control unit.

In the following, an explicit calculation for the increase of the pressure by a pressure pulse by means of actuation of the first valve at the pressure source will be described. The calculation for the reduction of the pressure by a pressure pulse by means of control of the second valve at the pressure sink is analogous.

For example, the following formula is used for the calculation of a rectangular pulse for the pulse duration Δt1 required for a pressure change Δp at preselected amplitude of the control signal (voltage, current) S1, where xi1 (analog xi2, see (*)) directly determines the desired final pressure p_soll and, under the specification of the final pressure p_set, one still has the freedom to choose the amplitude or the opening time: $$\mathrm{.delta.t}\mathrm{1}\left(\mathrm{et}\mathrm{1}.\mathrm{Ap}\right)=\mathrm{xi}\mathrm{1}\cdot \mathrm{R}\mathrm{1}\left(\mathrm{eta}\mathrm{1}\right)\cdot \mathrm{C}$$

gelöst und daraus Δt1 bestimmt. Für komplexere Signalformen wird dies bevorzugt numerisch gelöst.For other time-dependent pulse forms R1 (eta1 (t)), the corresponding integral over the opening period Δt1 is preferred $$\mathrm{xi}\mathrm{1}\cdot \mathrm{C}=\int \mathrm{R}\mathrm{1}\left(\mathrm{eta}\mathrm{1}\left(\mathrm{t}\right)\right)\mathrm{dt}.$$

solved and determined from it Δt1. For more complex signal forms this is preferably solved numerically.

oder in linearer Näherung = Δt1/(xi1 C) gültig für nahezu lineare Kennlinien der Ventile. Aus dem Öffnungsgrad wird bevorzugt mit Hilfe der Kennlinie g1(S1)=eta1 (z. B. aus dem Datenblatt) direkt der Steuerstrom/die Steuerspannung S1 bestimmt.For the calculation of the opening degree eta1 required for a pressure change Δp at a preselected pulse duration Δt, z. For example, the following formula is used: $$\mathrm{eta}\mathrm{1}={\mathrm{f}\mathrm{1}}^{-\mathrm{1}}\left(\mathrm{.delta.t}\mathrm{1}/\left(\mathrm{xi}\mathrm{1}\cdot \mathrm{C}\right)\right)$$

or in a linear approximation = Δt1 / (xi1 C) valid for nearly linear characteristic curves of the valves. From the opening degree, the control current / control voltage S1 is preferably determined directly with the aid of the characteristic curve g1 (S1) = eta1 (eg from the data sheet).

This significantly improves the fast and stable achievement of the setpoint. Leaks or movements in the experiment and the supply lines may change the pressure. Therefore, predictive pulses are preferably used repeatedly.

The predictive packet method allows the precise and fastest possible shifting of objects and fluids in the microchannel with minimal noise. For an exact calculation, the temperature is preferably kept stable at 2.0 ° C., preferably 1.0 ° C., particularly preferably 0.1 ° C.

Preferably, the valves are stabilized with a Peltier element and a regulator, preferably in order to increase the reproducibility of the opening pulses and the pressure pulses generated thereby. Preferably, the valves are stabilized at 27 ° C ± 0.5 ° C.

For the activation, a real-time system is preferably used which can generate signals with hundredths, particularly preferably milli, very particularly preferably micro and most preferably nanosecond precision.

• Ansteuern des ersten Ventils (10) in Form des Pulses mit einer ersten Pulsdauer und einer ersten Pulshöhe und/oder mit einem ersten Pulskurvenintegralwert und Ansteuern des zweiten Ventils (20) in Form des Pulses mit einer zweiten Pulsdauer und einer zweiten Pulshöhe und/oder mit einem zweiten Pulskurvenintegralwert
• Messen des Drucks in dem Mikro- oder Mesofluidik-Kanal (2)
• Bestimmen des Eingangsdrucks in Abhängigkeit von dem gemessenen Druck in dem Mikro- oder Mesofluidik-Kanal (2) und der zweiten Pulsdauer. In einer Ausführungsform der erfindungsgemäßen Vorrichtung ist diese eingerichtet einen solchen Eingangsdruck mittels dieser Schritte zu bestimmen.

In a further method according to the invention, an inlet pressure of the Micro or Mesofluidik channel (2) which abuts the first valve (10), determined by means of the steps

• Driving the first valve (10) in the form of the pulse with a first pulse duration and a first pulse height and / or with a first pulse curve integral value and driving the second valve (20) in the form of the pulse with a second pulse duration and a second pulse height and / or with a second pulse curve integral value
• Measuring the pressure in the micro or mesofluidic channel (2)
• Determining the input pressure in dependence on the measured pressure in the micro or mesofluidic channel (2) and the second pulse duration. In one embodiment of the device according to the invention, the latter is set up to determine such an inlet pressure by means of these steps.

The driving of the first and second valves preferably takes place one after the other. The pulse durations of the pulses with which the first and second valves are controlled, and preferably also the pulse height and / or the first and second pulse curve integral values, are preferably the same. Preferably, the first valve is opened for a short time so that the sensor can measure a value. Then the pressure over the opening of the second valve with the same opening time is preferably relieved to the atmosphere or to the low pressure input. The relaxation takes place exponentially, and the waste rate, or the residual pressure after a given opening time allows the calculation of the inlet pressure. This method is also preferably carried out for negative pressures.

The input pressure is preferably determined by means of the following formula: p_in = p_i ² / (p_i-p_e)

Here, p_in is the input pressure to be determined p1 (pressure source) or analogous to the output pressure p2 (pressure drop), p_i is the pressure in the system after opening the first valve, p_e is the pressure in the system after opening the second valve. The second valve relaxes the pressure to the atmosphere or to a pressure source / sink of known pressure.

Example: The first valve and the second valve are opened consecutively for 75 ms. After opening the first valve, the initial pressure p_i = 338 mbar and after opening the second valve, the final pressure p_e = 292 mbar, the difference is 46 mbar and thus p_in = (338 mBar) ² / (46 mBar) = 2484 mBar.

The inlet pressure is thus about 2.5 bar. This pressure is z. B. of small standard pressure bottles (eg., 600ml) for cleaning purposes. Preferably, the pressure at the outlet (if different from the atmospheric pressure) is determined analogously.

In a further method according to the invention, the activation of at least one of the valves (10, 20) in the form of at least one pulse leads to an unpulsed or continuous mode of operation or from the non-pulsed mode to the actuation of at least one of the valves (10, 20). ignored in the form of at least one pulse. The device is preferably set up to carry out such a transition.

Preferably, a transition occurs slidably. For this purpose, the minimum valve opening degree is preferably increased until there is no or only a small difference between the valve opening degree, which corresponds to the amplitude resulting from regulation, and the minimum valve opening degree. Alternatively or additionally, the maximum amplitude that can be set for regulating the pulse duration (thus the maximum valve opening degree) is reduced so far that the pulse widths become maximum and the pulses fuse together. In this case, a continuous transition to the initially described continuous processes (eg the process with negative feedback of the valves) is carried out. During the execution of a transition from one to the other operating mode, it is preferable not to take into account the condition possibly set for pulsed operation that only one valve may be opened at a time or at least one valve must be in the state of the minimum valve opening degree.

For example, a triggering by pulses is first performed to roughly approximate the actual value of the pressure to the setpoint, and then to an unpulsed mode of operation. If the actual value is further away from the setpoint, eg. B. by a setpoint change, is again transferred to the pulsed mode. In addition or in addition z. B. transitioned from a pulsed to an unpulsed mode when a leak in the system sets, so that the system is no longer tight. Once the leak is gone, the pulsed mode is transitioned.

In a further inventive method , an input pressure in the micro and / or Mesofluidik channel (2) is set higher than the desired pressure range in the micro and / or Mesofluidikkanal (2) and / or an output pressure from the micro and / or Mesofluidik Channel (2) is set lower than the desired pressure range in the micro and / or mesofluidic channel (2). In an apparatus according to the invention, such an inlet pressure and / or outlet pressure are preferably adjustable.

The inlet pressure is z. B. the voltage applied to the first valve, the output pressure z. B. the voltage applied to the second valve.

In this way the internal inertial inertness of the system is minimized. The dynamics are particularly preferably significantly improved by the input pressure is above the maximum target pressure and the output pressure below the minimum target pressure. As a result, the parts of the exponential decay function are preferably used, which have a high slope.

Figur 1

eine Übersicht über eine erfindungsgemäße Vorrichtung zur Veranschaulichung des erfindungsgemäßen Verfahrens,

Figur 2

Graphen für den zeitlichen Verlauf des Steuersignals S und des Drucks P im Mikrokanal eines Ansteuerns eines Ventils in Form eines Rechteckpulses,

Figur 3

den zeitlichen Verlauf des Drucks P im Mikrokanal einer Regelung gemäß Stand der Technik, bei dem nur eines der beiden Ventile geregelt wird und kein Unterdruck an einem der Ventile angeschlossen ist,

Figur 4

den zeitlichen Verlauf des Drucks P einer erfindungsgemäßen Regelung beider Ventile wobei an einem der Ventile ein Über- und an dem anderen der Ventile ein Unterdruck angeschlossen ist,

Figur 5

einen zeitlichen erfindungsgemäßen Verlauf der Steuersignale S1 für das erste und S2 für das zweite Ventil und den resultierenden Druckverlauf P im Mikrokanal

Figur 6

einen Verlauf des Rauschverhaltens eines erfindungsgemäßen Verfahrens mit Regelung von Druckpulsen bei eingestellter schneller Dynamik der Regelung durch Steuerpulse,

Figur 7

einen Verlauf des Rauschverhaltens eines erfindungsgemäßen Verfahrens mit Regelung von Druckpulsen nach einer weiteren kurzen Zeitspanne,

Figur 8

die Abhängigkeit der durch die erfindungsgemäßen Steuerpulse erzeugten Druckpulse von Temperaturschwankungen,

Figur 9

den Effekt einer erfindungsgemäßen Stabilisierung der Temperatur zur Steuerung/Regelung des Drucks im Mikrokanal,

Figur 10

den Übergang von einem Pulsbetrieb in einen kontinuierlichen Betrieb nach einer ersten Variante,

Figur 11

den Übergang von einem Pulsbetrieb in einen kontinuierlichen Betrieb nach einer zweiten Variante.

The invention will now be further illustrated by way of example with reference to the drawings. Hereby show:

FIG. 1

an overview of a device according to the invention for illustrating the method according to the invention,

FIG. 2

Graphs for the time course of the control signal S and the pressure P in the microchannel of a control of a valve in the form of a rectangular pulse,

FIG. 3

the time profile of the pressure P in the microchannel of a control according to the prior art, in which only one of the two valves is regulated and no negative pressure is connected to one of the valves,

FIG. 4

the time profile of the pressure P of a control according to the invention of both valves, wherein a negative pressure is connected to one of the valves and to the other of the valves,

FIG. 5

a temporal course according to the invention of the control signals S1 for the first and S2 for the second valve and the resulting pressure curve P in the microchannel

FIG. 6

a course of the noise behavior of a method according to the invention with regulation of pressure pulses with set fast dynamics of the control by control pulses,

FIG. 7

a course of the noise behavior of a method according to the invention with regulation of pressure pulses after a further short period of time,

FIG. 8

the dependence of the pressure pulses generated by the control pulses according to the invention on temperature fluctuations,

FIG. 9

the effect of stabilizing the temperature according to the invention for controlling the pressure in the microchannel,

FIG. 10

the transition from a pulsed operation to a continuous operation according to a first variant,

FIG. 11

the transition from a pulsed operation to a continuous operation according to a second variant.

FIG. 1 shows an overview of a device according to the invention for illustrating the method according to the invention. On the left side is indicated by an arrow the input of the system to which a pressure source is connected. This is directly connected to the first valve 10. Between the valve 10 and the valve 20 is an area with which a microchannel 2 is in pneumatic or hydraulic connection. On the right side is indicated by an arrow the output of the system, which is connected to a pressure sink. The gas flow passes through the system from left to right. The device 1, not restrictively indicated here as a computer, is set up to send control signals to the valves 10, 20. Optionally, a pressure sensor is shown, which is set up to measure the pressure between the valves 10, 20 and forward it to the device.

In operation of the invention, the pressure in the microchannel 2 is changed by means of actuation of the valves 10, 20 (eg for positioning of cells for microscopic observation). The valves change their respective valve opening degrees and, due to the ratio of the valve opening degrees, a certain pressure is established in the microchannel 2. For driving the device 1 sends control signals to both valves 10, 20, wherein the control signals for the one valve 10 are dependent on the control signals of the other valve 20 (and / or vice versa).

In this way, the control is simplified, although both valves are controlled and thus a more flexible control z. B. different System work points is possible, since one of the valves is automatically mitgesteuert.

FIG. 2 shows graphs of the time course of the control signal S and the pressure P in the micro-channel for driving the valve 10 (input valve) in the form of a rectangular pulse. The valve 20 (output valve) is fixed and slightly open, causing too slow decay behavior. Here a pressure pulse with a very low pulse height and long pulse duration is shown. With a short pilot current pulse to the high amplitude valve, the pressure pulse becomes steeper and shorter until a limit dynamic is reached, which is determined by the resistance of the valves, the applied pressures and the system volume.

FIG. 3 shows the time course of the pressure P in the microchannel of a control according to the prior art, in which only one of the two valves is controlled and no negative pressure is connected to one of the valves. Shown is a typical pressure dynamics of a change from -200 to +200 mbar and again to - 200 mbar for a single-valve system with PID control. In addition to the lack of activation of the second valve, the missing negative pressure significantly worsens the dynamics, since the setpoint pressure 0 mbar is only approximated by an exponential curve, even when the second valve 20 is completely open. Also clearly visible are overshoots in response to a pulse.

FIG. 4 shows the time course of the pressure P of a control according to the invention both valves 10, 20 wherein at one of the valves 10, 20, a positive pressure and at the other of the valves 10, 20, a negative pressure is connected. Both the pressure drop flank and the pressure rise flank are significantly steep and uniform in contrast to the previous figure.

First, the second valve 20, which is connected to the pressure sink, fully opened, so that the pressure drop is maximum fast, kept open and then closed again. This control corresponds to a square pulse. Thereafter, the first valve 10, which is connected to the pressure source, fully opened, kept open and closed again, which corresponds to the driving in the form of a further rectangular pulse. The pulse height and / or the pulse duration are additionally varied during the control as a control variable for the regulation of the pressure in a PID control loop, so that the overshoots are significantly attenuated after reaching the setpoint. In this way, both flanks of the pressure change are maximally steeply generated. The connection of a negative pressure to the second valve 20 additionally amplifies this steepness. This achieves a linear and abrupt decrease. Furthermore, at the time when both valves are completely closed, no gas flow and thus a total gas flow only for a short time, whereby the gas consumption is reduced to the essentials.

FIG. 5 shows a time course according to the invention of the control signals S1 for the first and S2 for the second valve and the resulting pressure curve P in the microchannel. The pressure should rise from one level to a higher level, then be lowered to a medium level.

For this purpose, first the first valve 10 is actuated at the pressure source by means of a pulse, as a result of which the first desired value is reached. Here, the parameterization of the required control pulse S1 takes place via a predictive calculation based on the required pressure change. Subsequently, the valve 20 is opened to the atmosphere or to the low pressure input by means of another predictively calculated control pulse S2. In this case, the dependence between the control pulses of the valves is taken into account that always at least one valve has a minimum valve opening degree.

In this way, a quick adaptation to the target pressure with minimum gas consumption and optimal dynamics can be realized.

FIG. 6 shows a course of the noise behavior of a method according to the invention with control of pressure pulses with set, fast dynamics of the control by control pulses. With fast dynamics, for example, after rapid changes in the target pressure, the noise caused by the control in the pressure signal is still relatively large: here about 20dB above the system's own noise by z. As electronics, thermal movement, semiconductors.

By adjusting the pulse height and pulse duration of the control pulses of both valves, the control noise is affected. To reduce the noise, the pulse heights are minimized and the pulse durations maximized. Fast dynamics with higher noise are set by larger pulse heights and shorter pulse durations.

FIG. 7 shows a profile of the noise behavior of a method according to the invention with control of pressure pulses after a further short period of time.

In this example, the pulse amplitudes are reduced after approaching the set point and thus the control noise is reduced. It is typically about 15dB above system noise.

FIG. 8 shows the dependence of the pressure pulses generated by the control pulses according to the invention of temperature fluctuations. The lower curve shows the modulation of the temperature by ± 5 ° Kelvin for this illustration. The control voltage for the valve is always pulsed in the same way. The resulting pressure curve shows a clear dependence on the temperature profile and is therefore faulty.

FIG. 9 shows the effect of a stabilization of the temperature according to the invention for controlling the pressure in the microchannel. The temperature curve is stabilized. Clearly visible is the constancy of the pressure changes without temperature-related fluctuation. The temperature is stabilized by commercially available temperature controllers and Peltier elements, which are placed on the valves.

FIG. 10 shows the transition from a pulsed operation to a continuous operation according to a first variant. The base level is raised in the case of leakage to the level of the control pulses S, so there is no difference. Thus, the pulses fall away and there is only a continuous control instead. The driving of the one valve is dependent on the driving of the other valve.

FIG. 11 shows the transition from a pulsed operation in a continuous operation according to a second variant. The pulse height is lowered so far and thus the pulse width expanded so far that the control pulses S merge together. Thus, a continuous signal is obtained.

With this invention, an apparatus and a method is presented, which represents a significant improvement in the prior art, the control and manipulation of the pressure in a microchannel. It's not just both Valves controlled automatically. The control of both valves also takes place in a simple, preferably even mutual dependence between the controlled valves. In this way, optimizable parameters are definable, z. As gas consumption, dynamics of changes, edge steepness, leakage compensation, negative feedback, control noise, etc. and a linear and effective control of the pressure is possible. In addition, system parameters (internal volume, displacement volume of a gas pulse, the gas particles shifted with a pulse and / or the input pressure) can be measured, whereby further predictive control can be carried out by calculating pressure pulses required for a pressure change using one or more of these parameters.

reference numeral

1

Device for regulating the pressure in a micro- or mesofluidic channel,

2

Micro- or mesofluidic channel,

10

first valve,

20

second valve.

Claims (15)

Method for controlling the pressure in a micro- or mesofluidic channel (2) by means of a first (10) and at least one second valve (20), wherein the first valve (10) has a first adjustable valve opening degree and the at least second valve (20) having at least a second adjustable valve opening degree, comprising the steps of: Driving the first valve (10) to set the first valve opening degree, Driving the at least second valve (20) to set the at least second valve opening degree,
characterized in that
the control of one of the valves (10, 20) takes place automatically and in response to the activation of another of the valves (10, 20). Method according to claim 1,
wherein the dependence of the driving of one of the valves (10, 20) on the driving of the other of the valves (10, 20), a counter coupling of the driving of the one of the valves (10, 20) and the driving of the other of the valves (10, 20 ) includes. Method according to claim 2,
wherein the negative feedback as a condition includes keeping constant the sum of a first flow resistance of the first valve (10) and a second flow resistance of the second valve (10). Method according to one of the preceding claims,
wherein for the first valve (10) a first minimum valve opening degree is defined or defined and for the at least second valve (20) an at least second minimum valve opening degree is defined or defined and the dependence of the driving of the one of the valves (10, 20) from the driving of the other of the valves (10, 20) includes the condition that is always set for at least one of the valves (10, 20) of the respective minimum valve opening degree by the driving of the valves (10, 20). Method according to one of the preceding claims,
wherein by the driving of the first valve (10) and the driving of the at least second valve (20) a preferably uninterrupted course of the pressure in the micro or mesofluidic channel (2) is set with positive and negative pressure values. Method according to one of the preceding claims,
wherein the driving of at least one of the valves (10, 20) in the form of at least one pulse for generating at least one pressure pulse in the micro or Mesofluidik channel (2). Method according to claim 6,
wherein the number of gas particles displaced with one of the generated pressure pulses is determined in the microfluidic or mesofluidic channel (2) and / or the volume displaced by one of the generated pressure pulses is determined in the microfluidic or mesofluidic channel and / or the internal volume of the Micro or mesofluidic channel (2) is determined. Method according to claims 6 to 7,
wherein the at least one pulse has a long pulse duration and / or a high pulse height and / or a large pulse curve integral value for coarse positioning of objects and / or fluids in the micro- or mesofluidic channel (2) and the at least one pulse has a shorter pulse duration and / or or has a lower pulse height and / or a small pulse curve integral value for fine positioning. Method according to claims 6 to 8,
wherein a measured variable in the micro- or mesofluidic channel (2), in particular the pressure, is controlled by repeatedly activating the valves (10, 20) in the form of the at least one pulse to a desired value. Method according to claim 9,
wherein control is effected by means of a regulation and a reaction speed and / or control noise of the control is freely selected and / or adapted by an algorithm to application requirements. Method according to claims 6 to 10,
wherein a pulse duration and a pulse height and / or a Pulskurvenintegralwert the at least one pulse in response to a change in pressure to be achieved in the micro or Mesofluidik channel (2) can be determined. Process according to claims 6 to 11
wherein an input pressure of the micro or mesofluidic channel (2) which is applied to the first valve (10) is determined by means of the steps: - Driving the first valve (10) in the form of the pulse with a first pulse duration and a first pulse height and / or with a first pulse curve integral value and driving the second valve (20) in the form of the pulse with a second pulse duration and a second pulse height and / or with a second pulse curve integral value Measuring the pressure in the micro or mesofluidic channel (2) Determining the input pressure as a function of the measured pressure in the micro- or mesofluidic channel (2) and the second pulse duration. Method according to claims 6 to 12,
wherein the driving of at least one of the valves (10, 20) in the form of at least one pulse to a non-pulsed mode is passed or is passed from the non-pulsed mode to the driving of at least one of the valves (10, 20) in the form of at least one pulse. Method according to one of the preceding claims, wherein an inlet pressure in the micro and / or Mesofluidik channel (2) is set higher than the desired pressure range in the micro and / or Mesofluidikkanal (2) and / or an output pressure from the micro and / or mesofluidic channel (2) is set lower than the desired pressure range in the micro and / or mesofluidic channel (2). Device (1) for controlling the pressure in a micro- or mesofluidic channel (2) by means of a first (10) and at least one second valve (20), wherein the first valve (10) has a first adjustable valve opening degree and the at least second valve (20) has an at least second adjustable valve opening degree, wherein the device (1) is arranged to: Driving the first valve (10) to set the first valve opening degree, Driving the at least second valve (20) to set the at least second valve opening degree,
characterized in that
the device (1) is further adapted to perform the driving of one of the valves (10, 20) automatically and in response to the driving of another of the valves (10, 20).

Images