Design of a multi-sensor readout chip for amperometric, potentiometric, impedometric, and colorimetric bio-sensor applications

Point-of-Care Testing (POCT) devices are being deployed to provide personalized healthcare monitoring or for remote monitoring whenever there is no accessible medical facility. In line with POCT, Lab-on-a Paper or Lab-on-a-Chip devices are taking flight. These include the hybrid of the sensor and readout circuit fabricated into a chip. To date, there is no single chip solution that harmonizes the four electrochemical sensing modalities which is the contribution of this work. The design of a multi-sensor readout chip is presented; this is composed of amperometric, potentiometric, impedometric, and colorimetric readout circuits implemented on TSMC 0.18 μm 1P6M technology. The chip can be used to implement a POCT to assist a patient in assessing the condition of his urinary system through urine quality indicators such as: pH value and ionic concentration of calcium (Ca2+) via potentiometric sensing; uric acid, citric acid, and calcium oxalate concentrations via amperometric sensing; osmolality or total dissolved salts through impedometric sensing; and urine turbidity, color and crystallization through its optical properties. The readout circuit designs for diversified sensing mechanisms were developed and investigated in this paper. In addition, a power savings of ~60dB can be achieved when all the circuits of the proposed chip are disabled. The sub-circuit enable was implemented using PMOS pass transistors. Non-simultaneous sub-circuit enable both reduces the power budget and prevents the inter-sensor interference or cross-talk.