WO2003052865A2

WO2003052865A2 - Device and method for measurements of the osmolality of aqueous solutions, utilizing multi-frequency electromagnetic waves, in the radio-frequency range

Info

Publication number: WO2003052865A2
Application number: PCT/IL2002/001012
Authority: WO
Inventors: Elazar Eyal-Bickels; Shulamit Margaliot
Original assignee: Elazar Eyal-Bickels; Shulamit Margaliot
Priority date: 2001-12-18
Filing date: 2002-12-17
Publication date: 2003-06-26
Also published as: AU2002361474A8; WO2003052865A3; WO2003052865B1; AU2002361474A1

Abstract

The present invention consists of an RF source (1) generating RF waves at two frequencies or more. These are transmitted by an antenna (2), to a reception antenna (6), via a vessel (4) containing an aqueous solution. The reception antenna (6) is linked to a device (7) measuring the intensity of the received RF power at the various RF frequencies used. The RF intensities thus measured are compared, yielding the frequency dependence of the RF attenuation by the passage of the waves in the vessel. This frequency dependence is then compared to the RF attenuation frequency dependence, obtained by the same system on a set of reference solutions having known osmolalities, thus deriving the osmolality of the solution contained in said vessel.

Description

Device and method for measurements of the osmolality of aqueous solutions, utilizing multi-frequency electromagnetic waves, in the radio- frequency range.

Abstract:

A measurement device and method , for the non-invasive measurements of the effective osmolality (tonicity) of aqueous solutions, contained in non-metallic vessels (henceforth referred to as the measured object), is disclosed. The device consists of:

1. An RF generator capable of generating RF waves at two frequencies at least, which are fed to:

2. transmitting element (antenna) capable of transmitting said waves via part of the measured object.

3. means of attachment of said fransmitting element(s) to said object.

4. RF receiving element (antenna) also attached by appropriate means to said object and capable of picking- up said RF waves after having passed part of said object and being attenuated by this passage.

5. an analysis system, which receives the RF signals picked- up by said RF receiving element, measures the wave's intensities and uses these intensities to compute the RF attenuation coefficients of said object. This last computation is conducted by comparing the RF intensities measured with said measured object in position and in the absence of said object. The measurements in the absence of an attenuating object need to be conducted only once, and are considered a constant of the system.

It then uses the RF attenuation data thus obtained, to compute and represent the osmolality of the aqueous solution contained in said object.

The object measured might be a non-living object containing an aqueous solution, or it might be a part of a body of living tissue such as a plant, animal or human.

6. The output from said analysis system is used to provide an alarm signal, in case the effective osmolality deviates from its desired value or range of values, and to activate, when applicable, other devices which act to return the osmolality to its desired value.

Field of the invention;

The present invention relates to a device and method for the measurements of the effective osmolality (tonicity) of aqueous solutions, contained in non- metallic vessels (henceforth referred to as the measured objects) , utilizing radio-frequency electromagnetic waves, of at least two frequencies.

Background of the invention:

Osmolality of an aqueous solution is the concentration of solutes (mainly ionic) in water. This is commonly expressed in units of solute particles per unit volume of the solvent (mol/liter). The osmolality is the factor that determines the osmotic pressure, which is an essential factor in many processes, of scientific, industrial biological and medical nature.

The accurate measurement of osmolality is therefore of great practical value. The osmolality can be measured directly by various methods (for example - by measurement of the electrical conductivity of the solution) but these require drawing out samples from the solution, or the insertion of electrodes into it. In many instances it is inconvenient, especially in case of osmolality measurements in living tissue.

Detailed disclosure of the invention:

It is the aim of the present invention to measure the osmolality of aqueous solutions, contained in non-metallic vessels, in a non-invasive manner. The present invention is based on the physical fact that electromagnetic waves in the radio frequency region (henceforth referred to as RF radiation or RFR) are capable of penetrating freely non conducting bodies, bur interact strongly with aqueous solutions.

The nature of interaction of RFR with the aqueous solution is dependent strongly on the frequency:

- At radio frequencies below ~1.5 GHz, the fluctuating electromagnetic fields in the RFR, induce mainly translational motion of the dissolved ions.

- At frequencies higher than ~1.5 GHz this effect is gradually replaced by the induction of rotational motion of the water molecules themselves.

Both effects however, result in an energy transfer from the radio waves to the aqueous solution exposed to the RFR, and thus - in the attenuation of the intensity of the radio waves.

However, at the frequency range below -1.5 GHz ,(henceforth referred to as the lower frequency), this attenuation is dependent mainly on the quantity of the ionic solutes exposed to the RFR, while at frequencies above - 1.5 GHz (henceforth referred to as the higher frequency), the attenuation depends mainly on the quantity of water exposed to the RFR. The ratio of the RFR attenuations for the two RF waves, the one at the lower frequency and the other at the higher frequency, has been shown by the present inventors to be dependent on the ratio of the quantities of ionic solutes to water in the exposed object - namely; on the osmolality of the examined solution. At

The invention consists therefore of :

An RF generator capable of generating RF waves at two frequencies at least, which are fed to a transmitting element, capable of transmitting said waves via the object measured. The invention further includes means of attachment of said transmitting element to said measured object. In addition the invention includes an RF receiving element also attached by appropriate means to the another part of said measured object and capable of picking- up said RF waves after having passed part of said object, and being attenuated by this passage. The RF signals thus picked-up by said RF receiving element, are fed to an analysis system, wliich uses the ratio of the intensities of the received RF waves to compute the RF attenuation coefficients of said object, by comparing the RF intensities thus obtained, to those obtained in the absence of any measured object. Said analysis system then uses the RF attenuation ratio data thus obtained, to compute and represent the osmolality of the aqueous solution contained in said object. This computation is based on the results of a previously conducted series of calibration measurements, in wliich aqueous solutions of known osmolalities were ex-imined by the present device. The ratio of the lower frequency to higher frequency attehuation coefficients, at a given osmolality, as obtained in said calibration measurements, is henceforth referred to as the attenuation ratio of this given osmolality. The compilation of the attenuation ratios obtained for a wide range of osmolalities thus examined, is referred to henceforth as the look-up table of attenuation ratios. The attenuation ratio of each new measurement of an unknown osmolality is compared to the attenuation ratios in said look-up table, and the final osmolality level of the unknown sample is derived from said lookup table by interpolation, as applicable. Alternatively, an equation linking The attenuation ratios to the corresponding osmolality values is derived from said calibration measurements, and used to compute the osmolality value in unknown samples. The osmolality value thus obtained is then displayed on an appropriate visual display.

For those objects for which the value of the effective osmolality might have a critical significance (such as excessive loss or gain of fluids in living systems), is also used to provide an alarm signal, in case the effective osmolality thus measured deviates from its desired value. Alternatively, the output from said analysis system may be fed to another device capable of controlling the fluid balance of the measured object (by way of example: an IV infusion pump or an irrigating system) thus acting as a feed-back element, helping to restore the desired osmolality level.

In a preferred embodiment of the present invention, the frequencies used are 0.93 MHz and 2.75 GHz, with a total power output of lOmW (lOdBm).

The power is conveyed from the source to a transmission antenna, attached by appropriate means to one side of the measured object. The reception antenna is attached to said measured objected on it's other side, and receives the transmitted RFR, after it passes a part of the measured object. The reception antenna is connected to an RF power meter, the output of which is fed to a microprocessor, which is also controlling the RF power source. This microprocessor conducts in sequence the following steps:

1. periodically initiates a measurement sequence, or receives an order to do so from it's control console.

2. on beginning a measurement sequence, it activates the RF power source to transmit a 0.93 GHz wave for 10 mSec.

3. receives, measures and stores in memory the value of RF power measurement during said 10 mSec.

4. 2 mSec later, activates RF power source to transmit a 2.75 GHz wave for another lO mSec.

5. receives, measures and stores in memory the value of the RF power measurement during last 10 msec. 6. uses ratio between the two readings in 3 & 5 above, to compute the ratio of low to high frequencies attenuation, and to derive from that the osmolality value, by inteipolating on a look-up table of osmolality values versus attenuation ratios, obtained in a series of former calibration measurements, on the relevant osmolalities range.

7. outputs the computed osmolality value, in terms of mol/liter units, to a display or/and to another device (such as an IV infusion pump or an automatic irrigation system).

8. produce an alarm, if the osmolality value thus obtained falls outside a pre-deteimined range.

In another preferred embodiment of the present invention, the transmission and reception antenna are adjacently placed and attached to one side of the examined body. As will be appreciated by those skilled in the field of RF wave propagation, part of the RF energy is being absorbed by the examined body even in this configuration, thus enabling the measurement.

Summary of the invention:

It is therefore the object of the present invention to provide an RF device for the non-invasive measurement of the osmolality of aqueous solutions enclosed in non metallic vessels or bodies.

A further object of the present invention is to provide such a measurement device, employing at least two RF signals of at least two different frequencies, the one bellow 1.5GHz, and the other above 1.5 GHz, passing said signals via the measured object, and employing RF receiver and received power (or electromagnetic fields) measurement device, to deteπnine the attenuations of the RF signals by said passage, at said two frequencies. A further object of the invention is to provide an analysis system, linked to said power measurement device, and capable of computing the ratio of said attenuations, and of comparing it to the attenuations ratio obtained from similar aqueous solutions of various osmolalities, and thus determining the osmolality of the solution in die examined body or object.

Still a further object of the present invention is to provide a display system on which the osmolality measured by the device is displayed.

Yet another object of the present invention is to provide an alarm device, linked to, and controlled by said analysis system, to provide an alarm signal, in case the detected osmolality deviates significantly from a pre-determined desired range of osmolality values.

Still a further object of the present invention is to provide an output from said analysis system, to serve as a feed-back signal for other devices capable of controlling the osmolality of the examined solution.

A brief description of the drawing (figure 1).

1- a radio frequency (RF) source producing RF signals of at least two frequencies; one lower than 1.5 GHz and the other higlier than 1.5 GHz

2- transmission antenna for above RF signals.

3- The un-attenuated RF waves

4- Measured object (non metallic vessel, containing aqueous solution of interest)

5- Attenuated RF wave (due to passing in measured object)

6- Reception antenna

7- Control unit (microprocessor) incorporating RF transmitter controller, RF power (or electromagnetic field) meter, received power analysis system and appropriate software.

8- Alarm unit

9- Output to osmolality controlling unit ( IV infusion pump, automatic agricultural irrigation system, etc.)

10- Display

11 -input for external measurement initiation.

Claims

Claims:

1. a device for the non-invasive measurement of the osmolality of an aqueous solution contained in a non-metallic vessel or body, comprising:

a radio frequency generator, capable of producing radio waves, of at least two frequencies.

antenna for transmitting said radio waves.

appropriate means for attachment of said antenna in near proximity to the measured object, with die antenna being so positioned that part of die radio wave must pass via the measmed object. another antenna for receiving said radio wave after passing in the measured object.

appropriate means for attachment of last antenna to the near proximity of the examined body.

RF power (or electromagnetic fields) meter, capable of measuring the intensity of the radio waves received by the reception antenna. r control system comprising a microprocessor connected to the output of said RF power meter, and capable of computing the osmolality of the aqueous solution within the measured object, from the received RF powers.

Visual display, for displaying the results of the measurement, as computed by said microprocessor. alarm device comiected to the output of said microprocessor.

2. output channel from said microprocessor, to other devices. another output channel from said microprocessor, to the RF source, via which said microprocessor activates the RF source, to emit RFR . input channel into said microprocessor, used to initiate externally a measurement sequence .

3. The system as claimed in claim 1, wherein said RF generator emits RF radiation at two frequencies at least, the one below 1.5 GHz and the other above 1.5 GHz

4. The system as claimed in claim 1, wherein said microprocessor controls said RF generator, regarding frequency emitted, length of emission and timing of emission.

5. The system as claimed in claim 1, wherein said microprocessor is connected to output of said power meter and capable of tiansforming received RF intensities to numerical values.

6. The system as claimeάVin claim 1, wherein said microprocessor is capable of computing the ratio between the received (attenuated) RF intensities at the above-mentioned two frequencies (henceforth referred to as the attenuation ratio).

7. The system as claimed in claim 1, wherein said microprocessor holds in memory values of a look-up table of osmolality levels versus attenuation ratios , and is capable of computing the osmolality in the current measurement, by comparing the attenuation ratio obtained in the current measurement, to said attenuation ratios in said look-up table, using an interpolation algorithm where needed, or alternatively, wherein said microprocessor holds in memory an equation linking osmolality values to corresponding attenuation ratios, as derived from the data of said look-up table.

8. The system as claimed in claim 1, wherein said microprocessor holds in memoiy a preset "normal" osmolalities range, and is capable of comparing the current result obtained, to said range, and of determining whether the current result falls out of said preset "normal" osmolality range, and if affirmative, activate an alarm.

9. The system as claimed in claim 1, wherein a visual display is connected to said microprocessor, and is capable of displaying the osmolality value computed by said microprocessor.

10. The system as claimed in claim 1, further including means for attachment of said transmission and reception antennas to the measure object.

11. A method for non-invasive measurement of the osmolality of aqueous solutions contained in non-metallic container or body, said method comprising:

providing a device as claimed in claim 1;

Introducing into memory of said microprocessor osmolality values and corresponding attenuation ratios, as obtained in a series of calibration measurements, previously conducted on solutions of known osmolality, ranging from below to above the normal osmolalities values.

Receiving RF signals passed via said measured object or body, analyzing received signals according to a preset algorithm, thus computing the osmolality of the aqueous solution contained in the examined body.

Comparing. the computed osmolality to a preset range of osmolalities, defined as "normal", and providing a visual, audible, visual or palpitating alarm if the computed osmolaUty falls out of said "normal" range.

Providing the computed osmolality as an output to other devices.

12. a device as claimed in claims 1 to 9, for the non-invasive measurement of the osmolality of an aqueous solution contained in a non-metallic vessel or body, substantially as hereinbefore described, and with reference to the accompanying drawing.

13. a method as claimed in claim 10, for the non-invasive measurement of the osmolality of an aqueous solution contained in a non- metallic vessel or body, substantially as hereinbefore described, and with reference to the accompanying drawing.