Dielectric layers for digital microfluidic devices
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-11801510-B2
Publication Date
2023-10-31
Expiration Date
Abstract
An electrowetting system is disclosed. The system includes electrodes configured to manipulate droplets of fluid in a microfluidic space. Each electrode is coupled to circuitry operative to selectively apply a driving voltage to the electrode. The system includes a dielectric stack including a first dielectric pair comprising a first layer having a first dielectric constant and a second layer having a second dielectric constant. The second dielectric constant is larger than the first dielectric constant. The dielectric stack includes a second dielectric pair comprising a third layer having a third dielectric constant and a fourth layer having a fourth dielectric constant. The fourth dielectric constant is larger than the third dielectric constant. A ratio of a thickness of the fourth layer to a thickness of the third layer (T4:T3) is in the range from about 2:1 to about 8:1. The second dielectric pair is thinner than the first dielectric pair.
Core Innovation
Digital microfluidic (DMF) devices, also referred to as electrowetting on dielectric (EWoD), rely on continuous actuation of droplets which over time can lead to unwanted electrochemical reactions that cause degradation of the dielectric layer stack overlaying the transistor matrix. Protecting against electrochemical degradation is difficult given aqueous solvents, salts and acids of many DMF reagents and relatively high voltages applied in the device, and keeping actuation voltages within ±30 V in TFT-based AM-EWoD devices has motivated the use of thin, high-k dielectric layers while exposing challenges of cost and manufacturing output.
The invention provides an electrowetting system comprising electrodes configured to manipulate droplets of fluid in a microfluidic space, circuitry operatively coupled to the electrodes to selectively apply drive signals, and a dielectric stack that includes a first dielectric pair comprising a first layer and a second layer wherein the second dielectric constant is larger than the first, and a second dielectric pair comprising a third layer and a fourth layer wherein the fourth dielectric constant is larger than the third and a ratio T4:T3 is in the range from about 2:1 to about 8:1, and the second dielectric pair is thinner than the first dielectric pair.
The disclosure further teaches multilayer dielectric stacks with alternating low-k and high-k dielectric pairs to combine high performance with resistance to electrochemical degradation, and describes embodiments in which portions of the stack are formed by Atomic Layer Deposition (ALD) and other portions by higher-throughput processes such as plasma-enhanced chemical vapor deposition (PECVD) to strike a balance between performance, lifetime, and manufacturing cost.
Claims Coverage
Overview: the patent includes three independent claims and three main inventive features extracted from those claims.
Dielectric stack with alternating dielectric pairs and specified thickness relationship
A dielectric stack comprising a first dielectric pair comprising a first layer and a second layer wherein the second layer has a dielectric constant larger than the dielectric constant of the first layer, and a second dielectric pair comprising a third layer and a fourth layer wherein the fourth dielectric layer has a dielectric constant larger than the dielectric constant of the third layer; a ratio T4:T3 is in the range from about 2:1 to about 8:1, and the second dielectric pair is thinner than the first dielectric pair.
Plurality of electrodes with circuitry to selectively apply drive signals
A plurality of electrodes configured to manipulate droplets of fluid in a microfluidic space, and circuitry operatively coupled to the plurality of electrodes to selectively apply drive signals to one or more of the plurality of electrodes.
Eight-layer dielectric stack with specified materials and thicknesses
A dielectric stack disposed over the plurality of electrodes comprising: a first dielectric layer formed of alumina (Al2O3) having a thickness of about 50 nanometers and a second dielectric layer formed of hafnium oxide (HfO2) having a thickness of about 50 nanometers forming a first dielectric pair; a third dielectric layer formed of alumina (Al2O3) having a thickness of about 5 nanometers and a fourth dielectric layer formed of hafnium oxide (HfO2) having a thickness of about 28 nanometers forming a second dielectric pair; a fifth dielectric layer formed of alumina (Al2O3) having a thickness of about 5 nanometers and a sixth dielectric layer formed of hafnium oxide (HfO2) having a thickness of about 28 nanometers forming a third dielectric pair; a seventh dielectric layer formed of alumina (Al2O3) having a thickness of about 5 nanometers and an eighth dielectric layer formed of hafnium oxide (HfO2) having a thickness of about 28 nanometers forming a fourth dielectric pair.
The independent claims principally cover (1) a multilayer dielectric stack architecture with alternating dielectric pairs and specified thickness ratios where thinner high-k/low-k pairs sit above a thicker pair, (2) an electrowetting system having a plurality of electrodes and circuitry to selectively apply drive signals, and (3) a specific eight-layer Al2O3/HfO2 stack with defined layer materials and thicknesses.
Stated Advantages
Combine high performance with resistance to electrochemical degradation.
Minimize the likelihood of pinholes forming throughout the entire thickness of the stack while operating at higher voltages and/or corrosive solutions.
Strike an optimal balance between expected results and operating expenses by combining high-quality deposition techniques and higher-output deposition processes.
Prevent the formation of pinholes while substantially reducing costs and deposition times and increasing production output.
Provide comprehensive protection for the TFT.
Documented Applications
Digital microfluidic (DMF) devices, also referred to as electrowetting on dielectric (EWoD) devices, used as a "lab-on-a-chip" for sample preparation, assays, and synthetic chemistry.
Active matrix EWoD (AM-EWoD) devices and TFT-based DMF devices with many thousands to millions of addressable electrodes for mass parallel assays and droplet procedures.
Droplet operations including loading, dispensing, splitting, separating, dividing, moving, merging, diluting, mixing, agitating, deforming, holding, incubating, heating, vaporizing, cooling, disposing, and transporting droplets in a microfluidic device.
Use with droplets containing biological samples or reagents, including 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 reagents for peptide and protein production.
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