Overcoming the sensitivity vs. throughput tradeoff in Coulter counters: A novel side counter design

Biosensors and Bioelectronics 2020, 168, 112507

Daniel T. Bacheschi, William Polsky, Zachary Kobos, Shari Yosinski, Lukas Menze, Jie Chen, and Mark A. Reed


The abstract reads as follows:¬†Microfabricated Coulter counters are attractive for point of care (POC) applications since they are label free and compact. However, these approaches inherently suffer from a trade off between sample throughput and sensitivity. The counter measures a change in impedance due to displaced fluid volume by passing cells, and thus the counter’s signal increases with the fraction of the sensing volume displaced. Reducing the size of the sensing region requires reductions in volumetric throughput in the absence of increased hydraulic pressure and sensor bandwidth. The risk of mechanical clog formation, rendering the counter inoperable, increases markedly with reductions in the size of the constriction aperture. We present here a microfluidic coplanar Coulter counter device design that overcomes the problem of constriction clogging while capable of operating in microfluidic channels filled entirely with highly conductive sample. The device utilizes microfabricated planar electrodes projecting into one side of the microfluidic channel and is easily integrated with upstream electronic, hydrodynamic, or other focusing units to produce efficient counting which could allow for dramatically increased volumetric and sample throughput. The design lends itself to simple, cost effective POC applications.

Research on the microfluidic design and electronic interfacing of the counting system at Yale was supported as part of the Center for Enhanced Nanofluidic Transport (CENT), an Energy Frontier Research Center funded by the US Department of Energy (DOE), Office of Science, and Basic Energy Sciences (BES) [award number DE-SC0019112 (water transport and particle counting studies)].