8 × 8 CMOS thermal sensors for enzymatic glucose detection

This work presents an 8 × 8 CMOS thermal sensor array for real-time, localized detection of the thermal energy produced by enzyme-catalyzed glucose reaction. The current of the PMOS sensing transistor is converted to a sawtooth-like waveform whose slope increases with respect to the temperature. Each of the sensing transistors occupies an area of 25 μm by 23 μm, which is suitable for use in metabolic monitoring at cellular level. The measured thermal sensitivity is about 5 mV/°C, close to the value of 5.3 mV/°C predicted by simulations. Detection of 0.5 M glucose has been successfully demonstrated by the array. The measured detection limit is 0.1°C, equivalent to detectable glucose concentration of 22 mM.