FPGA-Based Lock-In Amplifier for Measuring the Electrical Properties of Individual Cells

We report the design and validation of a low-cost and portable FPGA-based lock-in amplifier (LIA) for measuring the dielectric properties of cells through electrical impedance spectroscopy (EIS). The proposed design uses the phase sensitive measurement principle which detects the signal at a particular reference frequency and rejects the rest. By closely integrating the LIA with a custom-built instrumentation amplifier and a microfluidic device, we demonstrate the excellent ability of the system to suppress noise and detect impedance changes due to flowing red blood cells (RBCs).