A low-noise gain-enhanced readout amplifier for induced molecular electronic signals

This paper reports a low-noise readout circuit for label-free, mobile detection of protein-ligand interactions. It is based on a new sensing technique where the surface charge of an electrode is altered due to the dipole moment of nearby biomolecules. We propose a low-noise readout circuit to measure the sub-nA signals. Using a chopped low-noise integrating preamplifier and a resistive transimpedance amplifier, the gain of the proposed circuit is 1.7 GΩ with an input-referred noise of 82 fARMS over a 10 Hz bandwidth. We demonstrate that the designed amplifier can capture the induced molecular electronic signature of Trypsin with a 50×50 μm² sensing electrode.