Impedance Characteristics of Microfluidic Channels and Integrated Coplanar Parallel Electrodes as Design Parameters for Whole-Channel Analysis in Organ-on-Chip Micro-Systems

• Published in: Biosensors (Basel) Vol. 14; no. 8; p. 374
• Main Authors: Rapier, Crystal E, Jagadeesan, Srikanth, Vatine, Gad D, Ben-Yoav, Hadar
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01-08-2024; MDPI
• Subjects: Advanced materials; Biochips; Biosensing Techniques; Biosensors; Blood vessels; Boundary conditions; Cell culture; Cell size; Design; Design parameters; electric cell substrate impedance spectroscopy (ECIS); Electric Impedance; Electric properties; Electrochemistry; Electrodes; Electrolytes; Environmental control; Equipment Design; Frequency ranges; Glass substrates; Humans; Impedance; impedance-based sensor; Lab-On-A-Chip Devices; Microfluidic Analytical Techniques; Microfluidic devices; Microfluidics; organ-on-a-chip; Real time; Sensors; Silicon wafers; Spectrum analysis; Thin films; Germany; Israel; United States > US; organ-on-a-chip; electric cell substrate impedance spectroscopy (ECIS); microfluidics; design parameters; impedance-based sensor
• DOI: 10.3390/bios14080374
• EISSN: 2079-6374

Microfluidics have revolutionized cell culture by allowing for precise physical and chemical environmental control. Coupled with electrodes, microfluidic cell culture can be activated or have its changes sensed in real-time. We used our previously developed reliable and stable microfluidic device for cell growth and monitoring to design, fabricate, and characterize a whole-channel impedance-based sensor and used it to systematically assess the electrical and electrochemical influences of microfluidic channel boundaries coupled with varying electrode sizes, distances, coatings, and cell coverage. Our investigation includes both theoretical and experimental approaches to investigate how design parameters and insulating boundary conditions change impedance characteristics. We examined the system with various solutions using a frequency range of 0.5 Hz to 1 MHz and a modulation voltage of 50 mV. The results show that impedance is directly proportional to electrode distance and inversely proportional to electrode coating, area, and channel size. We also demonstrate that electrode spacing is a dominant factor contributing to impedance. In the end, we summarize all the relationships found and comment on the appropriateness of using this system to investigate barrier cells in blood vessel models and organ-on-a-chip devices. This fundamental study can help in the careful design of microfluidic culture constructs and models that require channel geometries and impedance-based biosensing.