High sensitivity handheld analog readout circuit for microfluidic based electrical impedance sensing

In this paper, we present a novel lock-in-amplifier design analog readout of a microfluidic based impedance cytometer which is portable, low cost and capable of detecting 8 micron bead with a signal to noise ratio (SNR) of 184. Phase mismatch between sensor signal and the reference signal, which is a major concern in lock-in-amplifier design does not pose any problem in our detection technique. The circuit board was tested with gold electrodes micro-patterned on a glass substrate. This design can be further improved for submicron biological cell characterization and detection while we can miniaturize the circuit size and reduce cost significantly.