Fig. 4: Artificial sensory nerve, functioning as a nociceptor with high energy efficiency.

a Concept of the artificial nociceptor comprising hourglass-shaped microstructured capacitive pressure sensor and a flexible memristor. In this system, the pressure sensor and flexible memristor play as a tactile sensory receptor and neuron, respectively. b A circuit diagram for the nociceptor. A load resistor of 33 kΩ offers the sensitive changes of the electric potential at the memristor, in response to variations in the sensor’s capacitance. c Threshold characteristics of the nociceptor where input pressure pulses 1 s wide with different pulse amplitudes (0.25, 1.25, 2.50, 3.75, and 5.00 kPa). The interval between the pressure stimuli was 25 s. d Relaxation characteristics of the system. After application of 5.00 kPa pressure stimulus, a 1.25 kPa pressure pulse with different interval times was applied. e No adaptation properties of the system. A sequence of pressure pulses with 2.50 and 3.75 kPa was utilized. f Responses of the uninjured (0 kPa) and injured (10 and 15 kPa) systems to the input pressure stimuli composed of different amplitudes (0.25, 1.25, 2.50, 3.75, and 5.00 kPa). g Hyperalgesia and (h) Allodynia characteristics represented in the nociceptor system.