Integration of Ultra-Low Volume Pneumatic Microfluidics with a Three-Dimensional Electrode Network for On-Chip
Saurabh Tomar1, Charlotte Lasne1, Sylvain Barraud2
1Laboratory of Life Sciences Electronics, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
Micromachines
|July 2, 2021
Summary
Researchers developed a miniaturized pseudo reference electrode (RE) for Ion Sensitive Field Effect Transistors (ISFETs). This novel design integrates directly with microfluidics, eliminating post-processing and enabling scalable ISFET biasing.
Area of Science:
- Microelectronic Engineering
- Biomedical Engineering
- Materials Science
Background:
- Ion Sensitive Field Effect Transistors (ISFETs) require stable reference electrodes for accurate biasing.
- Traditional reference electrodes often necessitate complex post-CMOS fabrication steps.
- Miniaturization and integration of reference electrodes are crucial for advanced microfluidic and sensing applications.
Purpose of the Study:
- To introduce a novel, miniaturized pseudo reference electrode (RE) design for ISFETs.
- To demonstrate a fabrication process compatible with CMOS scaling and PDMS microfluidics.
- To evaluate the performance and stability of the developed pseudo-RE.
Main Methods:
- Utilized silane-mediated transfer of patterned gold electrode lines onto polydimethylsiloxane (PDMS) microfluidics.
- Developed "through-PDMS-vias" (TPV) using metal-coated SU-8 pillars for electrode access.
- Integrated the pseudo-RE network with pneumatic valves for biasing small electrolyte volumes.
- Characterized ISFET operation and DC performance; measured open circuit potential (OCP) against Ag/AgCl.
Main Results:
- Successfully fabricated and integrated a miniaturized pseudo-RE within PDMS microfluidics.
- Demonstrated effective biasing of 1.5 nanoliter (nL) isolated electrolyte volumes using the TPV and pseudo-RE network.
- Presented detailed characterization of ISFET operation and DC parameters.
- Investigated pseudo-RE stability through OCP measurements, showing comparable performance to commercial electrodes.
Conclusions:
- The novel pseudo-RE design eliminates the need for post-CMOS processing, offering a scalable solution for ISFET biasing.
- The integration of patterned gold electrodes, TPVs, and PDMS microfluidics provides a robust platform for miniaturized electrochemical sensing.
- The demonstrated stability and performance indicate the potential of this pseudo-RE for various microelectronic and biomedical applications.
