Fig. 3: The memory function of the optoelectrochemical synapse and its skin conformable form factor.

a Learning behavior in which only a few pulses (50) restore the memory gained through training with more pulses (100). The light pulse was at 375 nm with 200 mW cm^–2 intensity. b Complete associative learning process using two light sources with two wavelengths (\(\lambda\)=375 nm and \(\lambda\)=455 nm, 200 mW cm⁻²). This process is similar to the conditioned and unconditioned stimuli in Pavlov’s dog experiment. After the training (30 pulses of “bell”, 30 pulses of “beef” and 30 pulses of “bell” and “beef”), the conditioned stimulus (“bell”) can trigger unconditioned response (salivation). c The schematic diagram of optical logic functions of “AND” and “OR” operations of the optoelectrochemical synapse. The setup of optical logic functions of “AND” and “OR” operations is shown in Fig. S22b. The input (Light 1, 375 nm and Light 2, 455 nm) and output characteristics of the (d) “OR” operation and (e) “AND” operation. Light 1, “1”: a low illumination intensity (20 mW cm⁻²), and a high output current and “0”: no light, a low output current; Light 2, “1”: a high illumination intensity (100 mW cm⁻²), and a high output current and “0”: no light, a low output current. f The truth table of AND/OR logic functions. g Live/dead staining and cell viability. h The flexible and conformable optoelectrochemical synapse attached to skin. i The operating stability of the skin attached device. 100 pulses (375 nm, 200 mW cm^–2) with 0.1 s width and 0.1 s pulse interval were applied with a resting period of 98 s. The device was operated using commercial hydrogel as the electrolyte. V_D = V_G = 0.4 V.