WO2017094021A1

WO2017094021A1 - Controlled spontaneous three dimensional fabrication of micro/meso structures

Info

Publication number: WO2017094021A1
Application number: PCT/IN2016/000111
Authority: WO
Inventors: Prasanna GANDHI; Tanveer Ul ISLAM
Original assignee: Indian Institute Of Technology Bombay
Priority date: 2015-12-04
Filing date: 2016-04-29
Publication date: 2017-06-08

Abstract

Disclosed is a controlled spontaneous three dimensional fabrication of micro or meso structures using fluid instabilities. The method comprises dropping a measured quantity of a solution using a micro-pipette on a first surface of a first plate. The first plate has at least one of pre-defined protrusions or a pre-defined pits, on the first surface of the first plate. Further pressing a second plate against the first plate. The method further comprises lifting the second plate discretely and allowing air or any other low viscosity fluid to penetrate. Further the method comprises forming a structure having a plurality of branches. Further anisotropy on the first plate enables controlled formation of the plurality of branches.

Description

CONTROLLED SPONTANEOUS THREE DIMENSIONAL FABRICATION OF

MICRO/MESO STRUCTURES

TECHNICAL FIELD

[001] The present subject matter described herein, in general, relates to fabrication of fractal channels and structures, and more particularly to controlled fabrication of 3D fractal channels and structures spanning micro, meso and higher scales using fluid instabilities in "Hele Shaw cell".

BACKGROUND

[002] The existing method for developing patterns using Hele-Shaw cell of micron/nano meter sized particles of various materials such as minerals/oxides/sulphides/metals/ceramics may disclose use of a steadily expanding liquid-liquid interface. The interface may be populated using a suitable surfactant molecule that may spontaneously organize into superstructures. These superstructures may vary over large length-scales. However, such method may enable pattern formation without control over niether initiation nor evolution of various features being formed by the displacing or displaced fluid.

[003] Further, the existing techniques like lithography can only fabricate

2D structure.

SUMMARY

[004] This summary is provided to introduce aspects related to a method for controlled fabrication of 3D fractal channels and structures spanning micro, meso and higher scales using fluid instabilities in "Hele Shaw cell". This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.

[005] In one implementation a controlled spontaneous three dimensional fabrication of micro or meso structures using fluid instabilities is disclosed. The method may comprise dropping a measured quantity of a solution using a micro- pipette on a first surface of a first plate. The first plate has at least one of predefined protrusions or a pre-defined pits, on the first surface of the first plate. Further pressing a second plate against the first plate. The method may further comprises lifting the second plate and allowing air (or low viscosity fluid) to penetrate. Further the method may comprise forming a structure having a plurality of branches. Further anisotropy on the first plate enables controlled formation of the plurality of branches.

BRIEF DESCRIPTION OF THE DRAWINGS

[006] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer like features and components.

[007] Figure 1, illustrates a prior art in accordance with the present invention.

[008] Figure 2, illustrates a cell structure in accordance with the present subject matter.

[009] Figure 3, illustrates a flow chart, in accordance with the present disclosure.

[0010] Figure 4, illustrates an apparatus in accordance with the present disclosure.

DETAILED DESCRIPTION

[0011] The present subject matter discloses a method for controlled fabrication of 3D fractal channels and structures spanning micro, meso and higher scales using fluid instabilities in "Hele Shaw cell".

[0012] The present disclosure discloses a method for fabrication of fractal channels and structures. Further the fractal channels and the structures may be fabricated in a 3 dimensions in a controlled way. The fabrication method may be effective and inexpensive. Further the method may be implemented for micro, meso or higher scales using fluid instabilities in "Hele Shaw cell".

[0013] The Hele Shaw cell is an arrangement of narrowly spaced two plates in which a low viscous fluid like air displaces a relatively higher viscous fluid upon their separation. According to the present disclosure for no tip splitting condition the penetrating low viscous fluid fingers, like air, the layout may develop as an out-come of fingering competition between smaller suppressed and bigger dominant ones. Further the positions of developing branches may be controlled by introducing anisotropy on cell plate surfaces in the form of pits (negative structure) and lands (positive structure). Pits may act as the branch repellent while lands may act branch attractors.

[0014] According to the present disclosure the branches may be initiated from a defined point having a protrusion at the defined point or may be repelled at a defined point having pits at the defined point. Further upon initiation of the branches, the spacial progression of individual branches may be controlled by the rate of plate separation, and by pit and protrusion/land anisotropy.

[0015] According to another embodiment of the present disclosure the branches can be fabricated parallel to each other. The parallel branches can be obtained by having one of the two cell plates flexible and lifting by pulling the plate from one side making fluid-fluid interface such, that no finger remains behind or progresses further which could give rise to triple junctions (nodes) and thus parallel branched pattern. Again positioning of branches can be controlled by presence of pits and/or lands on the cell plates.

[0016] The present disclosure enables forming of structures on a layout created by displacing or displaced fluid. Further to control the initiation and position of the branches/finger.

[0017] Referring to Figure 1, illustrates a prior art in accordance with the present invention. According to the illustrated prior art 100 a quantity of fluid may be dropped using a micro-pipette on one plate of the cell and then may be squeezed to flow by pressing another plate on top of it. Further lifting back the top plate allows the air to penetrate as long air fingers leaving a highly fractal pattern on the plates. The suspension may spread in a form of a circular lamella as the high viscous suspension solution may displace the relatively low viscous surrounding fluid like air. The structures formed upon lifting the cell plate (parallely or at an angle) are spontaneous in nature and there is no control over the initiation and further positioning of the branches of structure formed.

[0018] Now referring to Figure 2, illustrates a cell structure in accordance with the present subject matter. In an embodiment of the present disclosure a first plate or a second plate may have at least one of pre-defined protrusions or a predefined pits. The first plate or the second plate may be flexible or rigid. The predefined protrusions or the pre-defined pits may positioned or located at defined position on the first plate or the second plate. In an exemplary embodiment the at least one of the pre-defined protrusions or the pre-defined pits may be on a first surface of the first plate. In another exemplary embodiment the at least one of the pre-defined protrusions or the pre-defined pits may be on a second surface of the second plate. The pre-defined protrusions or the pre-defined pits may vary in sizes of nano or micrometers range.

[0019] Further presence of anisotropy on the first plate or the second plate, may enable precise positioning of plurality of branches in the structure. Further by using the pits and protrusions/lands at the boundary of the first plate or the second plate the initiation of the plurality of branches may be controlled. The control can be achieved by making the air finger to penetrate at the location of pit and the branch origination from the location of protrusion.

[0020] According to the exemplary embodiment height or thickness of fractal branches formed may increase from periphery to the centre of the first plate or second plate, thereby giving the 3rd dimension to structures.

[0021] Referring to Figure 3, illustrates a flow chart, in accordance with the present disclosure. At step 302 a measured quantity of solution is dropped on a first surface of a first plate using a micro-pipette. Further the first plate may have at least one of pre-defined protrusions or a pre-defined pits, on the first surface of the first plate. In another exemplary embodiment a second surface of a second plate may comprise at least one of pre-defined protrusions or a pre-defined pits.

[0022] Further at step 304 the second plate may be pressed against the first plate spreading the solution across the first surface and the second surface of the first plate and second plate respectively. Further while spreading the solution forms a structure or pattern.

[0023] At step 306 the second plate is lifted discretely. The lifting of the second plate allow the air to penetrate and displace the solution. In an embodiment the second plate can be lifted while maintaining parallelity between the second plate and the first plate. In another exemplary embodiment the second plate may be lifted by a first edge and rotating the first edge about a second edge of the first plate.

[0024] Further at Step 308, a structure formed may have a plurality of branches. Anisotropy on the first plate or second plate may enable controlled formation of the plurality of branches. Further the structure formed may be solidified. The process for solidification may selected from heating, solution evaporation, or a UV curing, based on the solution used. Further according to the embodiment use of several high viscosity solutions: micro-nanoscale particles in polymer material, monomer solutions in volatile solvent, thermocuring plastics to name a few, use of several low viscosity solutions (air, water, etc) and further corresponding methods for solidification of formed structures.

[0025] Referring to Figure 4, illustrates an apparatus in accordance with the present disclosure. The apparatus 400 may comprise a first plate 01. The first plate 01 in may be rigid or flexible. The first plate 01, may further comprise a predefined protrusion 04, and/or pre-defined pit 05. The pre-defined protrusion 04, and/or the pre-defined pit 05 may be on a first surface of the first plate 01. Further according to the embodiment the position, and/or the dimension may be defined for the pre-defined protrusion 04, and/or the pre-defined pit 05. Further the apparatus 400 may comprise a second plate 02. According to the exemplary embodiment the second pate 02, may be pressed against the first plate 01, wherein the pressing be either at an angle or parallel to the first flat 01, as illustrated by the Figure 4 (a), wherein the dotted line show the parallel placement and the solid line illustrates at an angle. Further Figure 4 (b) illustrates a fluid film 06, developed when a fluid drop 03, is pressed between the first plate 01 and the second plate 02. When the first plate 01 and the second plate 02, are separated a structure 07 may develop on the first plate 01 and the second plate 02. As illustrated in Figure 4 (c). Further at figure 4 (d) a magnified view 08 of the fractal structure developed. In the exemplary embodiment a plurality of braches originate from the pre-defined protrusion 04 and away from the pre-defined pits 05.

Claims

WE CLAIM:

1. A controlled spontaneous three dimensional fabrication of micro or meso structures using fluid instabilities, comprising:

dropping a measured quantity of a solution using a micro-pipette on a first surface of a first plate, wherein the first plate has at least one of pre-defined protrusions or a pre-defined pits, on the first surface of the first plate;

pressing a second plate against the first plate;

lifting the second plate and allowing air to penetrate; and

forming a structure having a plurality of branches, wherein anisotropy on the first plate enables controlled formation of the plurality of branches.

2. The claim 1 , wherein the lifting of the second plate may further comprise of lifting the second plate while maintaining parallelity between the second plate and the first plate.

3. The claim 1, wherein the lifting of the second plate may further comprise of lifting the second plate by a first edge and rotating the first edge about a second edge of the first plate.

4. The claim 1, further comprises bordering the first surface with the pre-defined protrusions and enabling air to penetrate, enables origination of the plurality of branches from the pre-defined protrusions.

5. The claim 1, further comprises bordering the first surface with the pre-defined pits and enabling air to penetrate, enables initiation of the plurality of branches from the pre-defined pits.

6. The claim 1, further comprises solidifying the structure formed, wherein the structure is solidified using at least one of heating process, solution evaporation process, or a UV exposure process.

7. An apparatus for controlled spontaneous three dimensional fabrication of micro or meso structures using fluid instabilities, the apparatus comprising a first plate, characterized wherein the first plate has at least one of pre-defined protrusions or a pre-defined pits, on a first surface of the first plate.

8. The apparatus of claim 7, further comprises a second plate mounted on the first plate.

9. The apparatus of claim 8, wherein the second plate is flexible.

10. The apparatus of claim 7, wherein the first plate is flexible.