Fig. 3

a An image of the embedded platform with highlights of primary building blocks, including a test chamber in the middle with the gas inlet on the top and gas outlet is on the side. The BLE module is on a separated breakout board attached to the platform. b Smartphone connected over BLE in advertising mode showing bias levels of the four individual sensors. c The CDC FS Range was obtained by tuning the two configuration parameters C_range and T_conv individually. d The resulting bandwidth of front-end discrete-time integrators after configuring a T_conv time interval. e The resulting input offset and RMS noise of the CDC including the parasitic contribution of the PCB with the four inputs in an open state. f An example of the bias block for the unipolar V_bias1 to V_bias4 (bottom) and the bipolar V_bias5 (top) output including a timing example of one second bias period wherein the duty cycle is 0.7 s ON and 0.3 s OFF