CMOS Thermal Sensor Arrays for Enzymatic Glucose Detection

Miniaturized complementary metal-oxide semiconductor (CMOS) thermal sensor arrays are presented for real-time, two-dimensional temperature detection of the enzyme-catalyzed glucose reaction. The reaction is measured based on oxidation of glucose and decomposition of hydrogen peroxide, catalyzed respectively by glucose oxidase and catalase. The produced energy results in an increase of the source-to-drain current for the p-type sensing transistors. The measured sensitivity of the detection circuit was 5 mV/°C for an integration time of 4 μs. The average sensitivity of the 8 × 8 sensor array was 5.05 mV/M. A larger 16 × 16 sensor array has also been characterized. The spatial resolutions for the 8 × 8 and 16 × 16 sensor arrays were 20 × 20 and 43 × 34 μm
²
, respectively. The detectable temperature change was 0.14°C, equivalent to a detectable glucose concentration of 99 mM. The measured thermal time constant of the sensing transistor was about 25 μs.