Impedance-based Droplet Volume and Concentration Measurement in Digital Microfluidics

MEASUREMENT IN DIGITAL MICROFLUIDICS Gaurav J. Shah, Saman Sadeghi, Huijiang Ding, Supin Chen,, R. Michael van Dam Crump Institute for Molecular Imaging and Department of Molecular & Medical Pharmacology, Biomedical Engineering Department, University of California, Los Angeles, USA ABSTRACT In this paper, we report on simplified and improved impedance detection in digital microfluidics for measurement of volume or composition based on electrical properties of the liquids. Compared to other approaches reported in the literature, the platform discussed here simplifies the external circuitry to a single precision resistor and inexpensive DAQ module, while at the same time improving upon detection accuracy and sensitivity. The increased sensitivity of the device enables precise volume measurement as well as dynamic measurement of analyte concentration in droplets that could be applied to chemical or biochemical assays or process monitoring.