Figure 2.

In vitro assessment of electrical performance. (a) Average gain of a representative capacitively coupled transistor as a function of the input frequency (f) from 0.1 to 100 Hz. Inset shows the responses from this sensor node at 0.1 Hz (top) and 100 Hz (bottom), after band-pass filtering (0.05–568 Hz). (b) Power spectral density of a 5 mV AC signal at 10 Hz measured at a representative node, showing a typical 1/f relationship at low frequency. The input was a sine-wave of 5 mV at 10 Hz. (c) Histograms of noise (with Gaussian fitting) measured from all 396 nodes of the device in Fig. 1c. (d) Statistics of the threshold voltage (V_T) and peak effective mobility (μ_eff) of test transistors from 15 different arrays. (e) Statistics of yield (left) and gain (right) of 17 capacitively coupled, active sensing 18×22 electrode array. (f) Image of a device during a mechanical bending test. (g) Image of a device completely immersed in a saline solution, during a soak test. (h) Yield (Y, defined as the number of working nodes divided by the total number of nodes) as a function of cycles of bending to 5 mm bend radius, showing minimal changes up to 10000 cycles. (i) Electrical leakage current of 2 devices during soak testing. Minimal leakage appears over a period of 120 days at 37 °C. (j) Response of a representative node to a sine wave input (at 10 Hz) before, after 10000 cycles bending, and after saline immersion for 120 days.