Highly sensitive stretchable sensor combined with low-power memristor for demonstration of artificial mechanoreceptor properties

Abstract

The development of high-performance sensors emulating the response of the human skin to external mechanical stimuli is of increasing importance in the era of artificial intelligence and robotics. To realize artificial skin, various parameters must be met, including flexibility, biocompatibility and low power consumption of the employed sensors. In parallel, a multisensory platform for both detection and storage is required for emulating the physical properties of human skin. With this in mind, in this work we demonstrate an extremely sensitive resistive stretchable sensor that can achieve a gauge factor of ∼107 based on the employment of a polydimethylsiloxane (PDMS) substrate decorated with Pt nanoparticles as the stretch-sensitive medium placed in between two Ag electrodes. A critical step to achieve such performance is the formation of a rippled surface of the PDMS substrate through the combined use of pre-stretch and the deposition of a thin Al2O3 film by atomic layer deposition that enables the fabrication of highly stretchable Ag electrodes. The wavelength of the ripples, as well as the peak-to-valley height between them, can be directly controlled by tuning the applied pre-stretch load on the PDMS. By taking advantage of the extreme sensor sensitivity achieved, emulation of the functionality of a biological mechanoreceptor was further demonstrated by connecting the sensor in a parallel circuit configuration with a SiO2-based conductive-bridge memory. Various synaptic properties of the above sensory system are demonstrated, including paired-pulse facilitation and long-term plasticity, indicating the capabilities of our system to perform neuromorphic computations at the edge.