Fig. 3 | Nature Communications

Fig. 3

From: A biomimetic 2D transistor for audiomorphic computing

Fig. 3

Construction of neural auditory computational map. a Optical image and (b) zoomed in scanning electron microscope (SEM) image (false colored) of a biomimetic device for imitating the neural computational map inside the auditory cortex of barn owl. The device consists of multiple split-gates distributed along the length of the semiconducting MoS2 channel which is connected to the source and the drain metal contacts. These split-gates have constant lateral spacing of 400 nm and monotonically increasing vertical spacing from 200 nm to 600 nm. c Transfer characteristics of the device when each of the five colored pairs of split-gates are concurrently swept from 0 V to −30 V. d Color map of the inhibition ratio (IR) for all possible combinations of the split-gate pairs. IR is defined as the ratio of current through the device corresponding to VSG = 0 V and VSG = −30 V, concurrently applied to a given split-gate pair. IRs are significantly larger for split-gate pairs that are vertically aligned (diagonal elements in the color map). Within these vertically aligned pairs, the one with minimum split-gate spacing has the maximum IR and vice versa. e COMSOL simulation showing the 1D potential profile across the channel width for different split-gate spacing for VSG = −30 V applied to both split-gates. The magnitude of the potential in the ungated segment is much closer to the split-gate potential when the spacing is 200 nm compared to 600 nm and follows a monotonic trend as a function of the split-gate spacing. f Output current from the device when random voltage spikes of magnitude −30 V are applied to the two spilt gates corresponding to different spatial pairs. All pairs detect coincidence by suppressing the device current which is a digital operation, whereas, the device as a whole determines the location of coincidence through analog IR values. g Angular precision (Δθ) and corresponding number of analog computation levels (NP) as a function of the minimum difference between the analog IR values corresponding to two consecutive split-gate pairs (ΔIRD) for different current ON/OFF ratio of the semiconducting channel. Clearly, the biomimetic audiomorphic device can be designed to offer orders of magnitude better precision than the barn owl

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