Optical and electrochemical dual-image CMOS sensor for on-chip biomolecular sensing applications

A CMOS image sensor, which can sense optical images and 2D arrayed electrochemical profiles, was designed and fabricated. Target applications of the sensor include biomolecular microarray technology. An 8 × 8-pixel arrayed electrochemical sensor was successfully implemented into a 128 × 128-pixel APS CMOS image sensor. A current-sensing voltage follower was used as the column amplifier unit for electrochemical measurements. Eight column amplifier units were connected to electrochemical sensing pixels in each column one by one, and they function as on-chip potentiostats. The sensor can measure 2D arrayed voltammetry in an on-chip configuration. The basic properties and functions of the fabricated sensor were characterized. It was confirmed that optical and electrochemical imaging functions can be operated simultaneously and independently. The current range of the electrochemical measurement function was measured to be approximately 10 nA and 100 μA. A 2D arrayed cyclic voltammetry measurement was successfully demonstrated.