An Open-Source Add-On EVOM® Device for Real-Time Transepithelial/Endothelial Electrical Resistance Measurements in Multiple Transwell Samples

Abstract

This study provides design of a low-cost and open source add-on device that enhances the functionality of the popular EVOM® instrument for transepithelial/endothelial electrical resistance (TEER) measurement. The original EVOM® instrument is designed for measuring TEER in transwell samples manually using a pair of Ag/AgCl electrodes. The inconsistency in electrode placement, temperature variation, and a typically large (12–24 h) time interval between measurements result in large data variabilities. Thus, to solve the current limitation of the EVOM® instrument, we built an add-on device using a custom designed electronic board and a 3D printed electrode holder that allowed automated TEER measurements in multiple transwell samples. To demonstrate the functionality of the device prototype, we monitored TEER in 4 transwell samples containing retinal cells (ARPE-19) for 67 h. Furthermore, by monitoring temperature of the cell culture medium, we were able to detect fluctuations in TEER due to temperature change after the medium change process, and were able to correct the data offset. Although we demonstrated the use of our add-on device on EVOM® instrument only, the concept (multiplexing using digitally controlled relays) and hardware (custom data logger) presented here can be applied to more advanced TEER instruments to improve the performance of those devices.

Real-time measurement of the trans-epithelial electrical resistance in an organ-on-a-chip during cell proliferation

“…Many studies have shown that continuous electrical detection did not significantly influence the electrical properties of the cells. [43][44][45][46][47][48][49] The real-time measurement started after cell seeding for 6 hours. During the entire measurement process, the computer performed segmental fitting on the collected signals in real time by impedance.py.…”

Organ-on-a-Chip Platform with an Integrated Screen-Printed Electrode Array for Real-Time Monitoring Trans-Epithelial Barrier and Bubble Formation

“…21 Early forms of such electrical characterizations were performed using a pair of electrodes, popularly known as "chopstick" electrodes. 22 In this measurement approach, each stick of the electrode pair made of silver/silver chloride (Ag/ AgCl) is placed across a cell culture membrane with adherent epithelial cells. 23 The applied oscillating voltage across the electrodes induces a current that passes through the cells on both transcellular and paracellular paths.…”

“…However, no basolateral fluid compartment is present in the cells due to the adherence of the cells to the electrode, which excludes the employment of the ECIS setup in tight junction measurement. , On the other hand, trans-epithelial electrical resistance (TEER)-based measurement correlates the permeability of a cell layer with its electrical resistance. , This form of nondestructive electrical measurement can be utilized to assess the tight junctions where high and low electrical resistance correlates with tight and loose junctions, respectively . Early forms of such electrical characterizations were performed using a pair of electrodes, popularly known as “chopstick” electrodes . In this measurement approach, each stick of the electrode pair made of silver/silver chloride (Ag/AgCl) is placed across a cell culture membrane with adherent epithelial cells .…”