High-Density Redox Amplified Coulostatic Discharge-Based Biosensor Array

High-density biosensor arrays are essential for many cutting-edge biomedical applications including point-of-care vaccination screening to detect multiple highly contagious diseases. Typical electrochemical biosensing techniques are based on the measurement of sub-pA currents for micrometer-sized sensors requiring highly sensitive readout circuits. Such circuits are often too complex to scale down for high-density arrays. In this paper, a high-density 4,096-pixel electrochemical biosensor array in 180-nm CMOS is presented. It uses a coulostatic discharge sensing technique and interdigitated electrode (IDE) geometry to reduce both the complexity and size of the readout circuitry. Each biopixel contains an interdigitated microelectrode with a 13-aA low-leakage readout circuit directly underneath. Compared to standard planar electrodes, the implemented IDEs achieve a maximum amplification factor of 10.5× from redox cycling. The array's sensor density is comparable to state-ofthe-art arrays, all without augmenting the sensors with complex post-processing. The detection of anti-Rubella and anti-Mumps antibodies in human serum is demonstrated.