Generating waveforms, such as standing or propagating waves, in a multi-fluid electrowetting system

Patent metadata

Field	Value
Publication number	US-2016201699-A1
Application number	US-201614989322-A
Country	US
Kind code	A1
Filing date	Jan 6, 2016
Priority date	Jan 8, 2015
Publication date	Jul 14, 2016
Grant date	—

Abstract

A multiple-fluid system generates waveforms at its fluid interface, e.g. in a manner to prevent complete dewetting of a surface by the electrically non-conductive fluid and/or wetting of the surface by the electrically conductive fluid. In an example, a feedback controller senses capacitance across the non-conductive fluid, e.g. between one or more electrodes on the substrate and the conductive fluid. This first example controls voltages applied to the electrodes, based on the capacitive sensing, to create a static waveform, such as a standing wave, at the fluid interface. Another example manipulates the voltages applied to the electrodes to generate a propagating wave at the fluid interface.

First claim

What is claimed is:

1 . An apparatus, comprising:
a first substrate; a second substrate spaced from the first substrate to form a volume between the first and second substrates; first and second fluids, immiscible with respect to each other, in the volume between the first and second substrates, the first fluid being insulating and nearest to the first substrate, and the second fluid being conductive and nearest to the second substrate; electrodes formed adjacent to the first substrate and adjacent to the first fluid, at locations distributed across the surface of the first substrate; each respective one of the electrodes being configured to generate an electric field in the vicinity of the respective electrode extending through the first fluid, in response to a respective voltage applied to the respective electrode; and a controller coupled to control respective voltages applied to the electrodes to generate a complex waveform geometry at an interface between the first and second fluids.

2 . The apparatus of claim 1 , wherein the controller is further configured to control respective voltages applied to the electrodes so as to generate the waveform geometry without need for a contact angle change for the second fluid on an adjacent solid surface.

3 . The apparatus of claim 1 , further including a coating over surfaces of the electrodes, and in-between (a) the first fluid and (b) the surfaces of the electrodes and the surface of the first substrate.

4 . The apparatus of claim 3 , wherein the coating is a dielectric and/or is hydrophobic.

5 . The apparatus of claim 1 , wherein the controller is further configured to take a measure of electrical capacitance between one of the electrodes and the second fluid.

6 . The apparatus of claim 5 , wherein the controller is further configured to:
determine when the measured capacitance level is at an upper threshold for a period of time; and decrease the voltage level applied to the one electrode when the capacitance level is at the upper threshold indicating that the thickness level of the first fluid has reached a minimum.

7 . The apparatus of claim 6 , wherein the decrease in the voltage level when the capacitance level is at the upper threshold increases the thickness level of the first fluid to prevent complete dewetting by the second fluid.

8 . The apparatus of claim 6 , wherein the controller is further configured to:
measure the capacitance level at the one electrode to determine when the capacitance level is at a lower threshold for the period of time; and increase the voltage level applied to the one electrode when the capacitance level is at the lower threshold indicating that the thickness level of the second fluid has reached a maximum, wherein the increase in the voltage level when the capacitance level is at the lower threshold decreases the thickness level of the first fluid.

9 . The apparatus of claim 1 , wherein the first fluid is always between the second fluid and at least one of the electrodes carried by the first substrate.

10 . The apparatus of claim 1 , wherein the complex waveform geometry is static and comprises a non-symmetrical and/or non-spherical geometry.

11 . The apparatus of claim 1 , wherein the complex waveform geometry comprises a propagating wave.

12 . The apparatus of claim 1 wherein the first fluid and the second fluid are different in refractive index.

13 . The apparatus of claim 4 , wherein the controller is further configured to control respective voltages applied to the electrodes to at least substantially prevent dewetting of the dielectric and/or hydrophobic coating by the first fluid and/or wetting of the dielectric and/or hydrophobic coating by the second fluid.

14 . The apparatus of claim 13 , wherein the controller is further configured to control respective voltages applied to the electrodes to dynamically modulate thickness of the first fluid in an incomplete dewetting state relative to the dielectric and/or hydrophobic coating.

15 . The apparatus of claim 1 , wherein the controller is further configured to provide a sequence of voltages to a plurality of electrodes to enable a propagating waveform.

16 . The apparatus of claim 15 , wherein the controller further prevents the complete dewetting of a surface of the first substrate or a surface carried by the first substrate by the second fluid.

17 . The apparatus of claim 15 , wherein the controller is further configured to:
adjust the voltage level of each electrode from a maximum voltage level to a minimum voltage level after the waveform generated by each respective electrode reaches each succeeding electrode; and adjust the voltage level of each electrode from the minimum voltage level to the maximum voltage level when the waveform generated by each respective preceding electrode reaches each succeeding electrode, wherein the adjustment of the voltage level of each electrode between the maximum voltage level and the minimum voltage level generates the propagating waveform while preventing the complete dewetting of a surface of the first substrate or a surface carried by the first substrate by the second fluid.

18 . The apparatus of claim 1 , wherein the controller is further configured to adjust each voltage level of each electrode to generate a Fourier series approximation of a waveform that is imparted on the first fluid.

19 . The apparatus of claim 18 , wherein the controller is further configured to adjust a thickness level of the first fluid at each electrode based on the Fourier series approximation of the waveform that is imparted on the first fluid.

20 . The apparatus of claim 1 , wherein the apparatus is configured as at least one tunable optical element selected from the group consisting of: a lens, a prism, an array of lenses, an array of prisms, a diffraction grating, an optical phased array or a Fresnel lens.

21 . The apparatus of claim 1 , wherein the apparatus is configured as two or more optical elements that impart different optical effects.

22 . The apparatus of claim 1 , wherein the apparatus is configured to transport at least one fluid.

23 . The apparatus of claim 1 , wherein the apparatus is configured as a tunable optically reflective element.

24 . The apparatus of claim 23 , further comprising nano or micro-particles suspended between the first and second fluids to provide reflectivity at the interface, to configure the apparatus as the tunable optically reflective element.

25 . An apparatus, comprising:
a substrate; first and second fluids, immiscible with respect to each other, the first fluid being insulating and located between the substrate and the second fluid; a first electrode formed adjacent to the substrate and adjacent to the first fluid; the first electrode being configured to generate an electric field in the vicinity of the first electrode extending through the first fluid, in response to a voltage applied to the first electrode; a second electrode in contact with one of the fluids; and a controller coupled to the electrodes configured to measure capacitance between the first and second electrodes as an indication of thickness of the first fluid in vicinity of the first electrode and to control the voltage applied to the first electrode in response to the sensed capacitance.

26 . The apparatus of claim 25 , wherein the controller is further co

Assignees

• Abl Ip Holding Llc

Inventors

• Heikenfeld Jason Charles
• Hsieh Wan-Lin

Classifications

• B01L2400/0427

  Electrowetting · CPC title

• B01L3/502776

  specially adapted for focusing or laminating flows · CPC title

• B01L2300/168

  Specific optical properties, e.g. reflective coatings · CPC title

• B01L3/50273 Primary

  characterised by the means or forces applied to move the fluids · CPC title

• B01L2200/0636

  Focussing flows, e.g. to laminate flows · CPC title