Latched transistor driving for high frequency ac driving of EWoD arrays
Inventors
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Assignees
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NucleraNuclera develops automated benchtop platforms and integrated systems for rapid protein expression, optimization, and purification, utilizing cell-free synthesis, digital microfluidics, and software-driven workflows. Their technology enables miniaturized and scalable protein prototyping—including challenging targets such as membrane proteins—directly at the lab bench. Nuclera serves academic and industrial researchers, focusing on reducing turnaround time for functional protein access and streamlining screening and production. The company has secured significant funding to enable broad commercialization, expanded their leadership team to support scale-up, and continues to drive advancements in drug discovery, proteomics, and experimental automation.
Nuclera develops automated benchtop platforms and integrated systems for rapid protein expression, optimization, and purification, utilizing cell-free synthesis, digital microfluidics, and software-driven workflows. Their technology enables miniaturized and scalable protein prototyping—including challenging targets such as membrane proteins—directly at the lab bench. Nuclera serves academic and industrial researchers, focusing on reducing turnaround time for functional protein access and streamlining screening and production. The company has secured significant funding to enable broad commercialization, expanded their leadership team to support scale-up, and continues to drive advancements in drug discovery, proteomics, and experimental automation.
Publication Number
US-11410621-B2
Publication Date
2022-08-09
Expiration Date
Abstract
Methods and systems for driving an active matrix electrowetting on dielectric device including thin-film-transistors to increase the switching frequency of the propulsion electrodes beyond what is typical for line-by-line active matrix driving. By using a latching circuit, it is possible to selectively switch specific propulsion (pixel) electrodes between an “on” and an “off” state, wherein a propulsion electrode in an “on” state can be driven by a time varying drive voltage on the top electrode that is a much higher frequency than is typically possible with amorphous silicon thin-film-transistor arrays. The faster drive frequency improves the performance of electrowetting devices, especially when used with aqueous droplets having a high ionic strength.
Core Innovation
The invention provides an active matrix electrowetting on dielectric (AM-EWoD) system and a method of driving an AM-EWoD system that use a latching circuit to latch pixel transistors in an on state or an off state so that a time-variable voltage applied to a top plane common electrode can drive only latched on pixels. The pixel electrode of each pixel is connected to a pixel transistor whose gate is connected to a latching circuit, and after the desired gate pattern is latched the top plane common electrode is used to drive the entire pixel array at once so that only the latched on pixels are driven.
The invention addresses limitations of traditional line-at-a-time active matrix driving with a-Si TFT arrays where low frame rates allow ion diffusion through dielectric layers and lead to electrochemical reactions, device failure, and slowing of EWoD arrays. The latched transistor driving approach accommodates higher EWoD frame rates using persistent latched TFTs and a top plane electrode driver capable of driving the top plane electrode at high frequency while enabling implementation with simple design, standard low mobility a-Si TFTs at limited extra cost compared to memory-in-pixel techniques.
Claims Coverage
Eleven inventive features were identified across the independent system and method claims.
Processing unit
A processing unit that provides input instructions relating to droplet operations to be performed by the AM-EWoD system or method.
Pixel array with latching circuit
A pixel array in which each pixel comprises a pixel electrode, a pixel transistor whose source is operably connected to the pixel electrode and whose drain is operably connected to a matrix power rail, and a latching circuit operably connected to the pixel transistor gate, a matrix gate line, a matrix source line, and the matrix power rail, the latching circuit being configured to latch the pixel transistor in an on state or an off state controlled by the state of the matrix gate line and the state of the matrix source line.
Latch transistor and latching capacitor
A latching circuit that comprises a latch transistor having a source, a drain, and a gate operably connected to the matrix gate line and matrix source line, and a latching capacitor operably connected to the pixel gate, the drain of the latch transistor, and the matrix power rail.
Matrix gate and source drivers
A plurality of matrix gate drivers each operably connected to a matrix gate line and a plurality of matrix source drivers each operably connected to a matrix source line.
Power source and matrix power rails
A power source operably connected to the plurality of matrix power rails that are operably connected to pixel transistor drains.
Top plane common electrode providing time-variable voltage
A top plane common electrode disposed in opposition to the pixel array and operably connected to a top plane common electrode driver, the top plane common electrode being configured to provide a time-variable voltage to drive latched on pixels.
Controller configured to latch pixel transistors
A controller operably connected to the matrix gate driver, matrix source driver, and the top plane common electrode driver, the controller being configured to receive instructions from the processing unit to latch pixel transistors in an on state or an off state.
Thin film transistors including a-Si or metal oxide
An embodiment in which the pixel transistors and the latch transistors are thin film transistors (TFT), for example comprising a layer of amorphous silicon (a-Si TFT) or comprising a layer of metal oxide semiconductor.
Top plane driver frequency ranges
A top plane common electrode driver configured to provide a time-variable voltage having a frequency in ranges disclosed in the claims, for example between 250 Hz and 5 kHz, or between 500 Hz and 1.5 kHz, or between 750 Hz and 1.25 kHz, and which may be configured to operate at a frequency higher than or equal to the latch driving frequency.
Distributed controller architecture
A controller arrangement in which the controller may include a first sub-controller operably connected to the matrix gate drivers and matrix source drivers and a second sub-controller operably connected to the top plane common electrode driver.
Method of driving using latched pixels and top plane drive
A method comprising receiving input instructions into the processing unit relating to a droplet operation, outputting matrix gate line and matrix source line selecting instructions from the processing unit to the controller, outputting a matrix gate line signal and a matrix source line signal from the controller to switch the latching circuit of at least one pixel, and outputting a time-variable top common electrode signal from the top plane common electrode driver to drive latched on pixels.
The independent system claim and the independent method claim center on (1) an AM-EWoD pixel architecture that includes a latching circuit to latch pixel transistors on or off using matrix gate and source lines and (2) driving the latched pixel array by applying a time-variable voltage to a top plane common electrode, with supporting features including TFT implementations, specific top plane driver frequency ranges, power rails and driver architectures, and a controller arrangement.
Stated Advantages
Increase the switching frequency of the propulsion electrodes beyond what is typical for line-by-line active matrix driving.
Enable pixels to be driven by a time-varying drive voltage on the top electrode at a much higher frequency than is typically possible with amorphous silicon thin-film-transistor arrays.
Improve the performance of electrowetting devices, especially when used with aqueous droplets having a high ionic strength.
Accommodate higher EWoD frame rates using persistent latched TFTs and a top plane electrode driver while greatly simplifying driving of TFT hardware at higher frequencies at limited extra cost compared to memory-in-pixel techniques.
Higher-frequency driving results in less droplet 'slippage' during droplet protocols.
Documented Applications
Digital microfluidic (DMF) or electrowetting on dielectric (EWoD) devices used to propel, split, and join droplets to provide a 'lab-on-a-chip' for sample preparation, assays, and synthetic chemistry with nL to μL volumes.
Programmable AM-EWoD arrays for manipulating multiple droplets and executing simultaneous analytical processes, enabling massive parallelization of droplet procedures.
Droplet operations including loading, dispensing, splitting, transporting, merging, diluting, mixing, agitating, deforming, retaining, incubating, heating, vaporizing, cooling, disposing of droplets, and other electrode-mediated droplet operations.
Applications involving droplets that include biological samples and reagents, and protocols such as nucleic acid amplification protocols, affinity-based assay protocols, enzymatic assay protocols, gene sequencing protocols, protein sequencing protocols, and analyses of biological fluids.
Biochemical synthetic methods including reagents for synthesizing oligonucleotides and uses such as antisense oligonucleotides, siRNA, primers for DNA sequencing and amplification, probes for detecting complementary DNA or RNA, and tools for gene editing and artificial gene synthesis.
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