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[Display omitted] Applying a multi-modal sensing algorithm to a skin-like dual-channel self-powered sensor, which accurately detects real-time and continuous changes in pressure on the skin in response to variations in finger-applied force, while mitigating errors induced by temperature fluctuations. • A multimodal sensing algorithm compensating errors induced by temperature fluctuations. • Oxidation-stable metal-elastomer thermoelectric composite with a high pressure-sensitivity. • A self-powered sensor accurately detecting real-time continuous pressure changes. In the rapidly evolving field of electronic skins (e-skins), the development of self-powered sensors has emerged as a promising solution to providing continuous and reliable power sources for embedded sensors. This study introduces a novel approach that incorporates spike-shaped nickel (Ni) microparticles into a styrene-ethylene-butylene-styrene (SEBS) matrix, resulting in a thermoelectric material that functions as both an energy harvester and a pressure sensor, and a multimodal sensing algorithm designed to mitigate pressure sensing errors arising from temperature fluctuations in the thermoelectric self-powered pressure sensor. The Ni-SEBS composite, with a sensing mechanism that identifies changes in the Ni particle percolation state induced by compressive strain, exhibited a high sensitivity of 0.6234 kPa−1. Based on this composite, a dual-channel self-powered sensor was fabricated using the proposed algorithm and attached to the skin; the sensor successfully detected various forms of external pressure applied to the skin without errors due to temperature changes. [ABSTRACT FROM AUTHOR]

Soft biomimetic electronic devices primarily comprise an electronic skin (e-skin) capable of implementing various wearable/implantable applications such as soft human–machine interfaces, epidermal healthcare systems, and neuroprosthetics owing to its high mechanical flexibility, tissue conformability, and multifunctionality. The conformal contact of the e-skin with living tissues enables more precise analyses of physiological signals, even in the long term, as compared to rigid electronic devices. In this regard, e-skin can be considered as a promising formfactor for developing highly sensitive and transparent pressure sensors. Specifically, to minimize the modulus mismatch at the biotic–abiotic interface, transparent-conductive hydrogels have been used as electrodes with exceptional pressing durability. However, critical issues such as dehydration and low compatibility with elastomers remain a challenge. In this paper, we propose a skin-like transparent polymer-hydrogel hybrid pressure sensor (HPS) with microstructures based on the polyacrylamide/sodium-alginate hydrogel and p-PVDF-HFP-DBP polymer. The encapsulated HPS achieves conformal contact with skin due to its intrinsically stretchable, highly transparent, widely sensitive, and anti-dehydrative properties. We believe that the HPS is a promising candidate for a robust transparent epidermal stretchable-skin device. [ABSTRACT FROM AUTHOR]

Multi-functional electronic skin is of paramount significance for wearable electronics in health monitoring, medical analysis, and human-machine interfacing systems. In order to achieve the function of natural skin, mechanical sensing with high sensitivity is an important feature of electronic skin. Inspired by the spinosum structure under the skin, herein, we fabricate a new capacitive pressure sensor with two-dimensional transition-metal carbides and nitrides (MXene) and ferroelectric polymer (P(VDF-TrFE-CFE)) as an active layer and micropatterned Cr-Au deposited on polydimethylsiloxane as flexible electrodes. Such a method is facile, effective, easily operated, and low-cost. The device design provides great capacitive change as a consequence of large deformation under pressure. Benefiting from the randomly distributed microstructure and high dielectric constant of the active layer, the device demonstrates high sensitivity with great linearity (16.0 kPa−1 for less than 10 kPa), that is, a low detection limit of 8.9 Pa, and quick response. A series of dynamic physiological signals, including typing, knuckle motion, and voice recognition can be facilely detected, making it a competitive candidate in the field of wearable electronics. [ABSTRACT FROM AUTHOR]

Electronic skin imitates the function of human skin. The flexible pressure sensor is an important sensor of electronic skin. Although the flexible pressure sensor has made some progress, electronic skin is still a challenging subject with good pressure resolution, high sensitivity, and fast response ability in biomedical, human motion detection, personal health monitoring, and other fields. The PEDOT:PSS/GR/SWCNTs multicomponent solution was directly written on the flexible PDMS substrate by the near-field electrohydrodynamic direct-writing method, a serpentine shaped pressure sensitive unit was prepared, which was encapsulated with the PDMS thin film, and the flexible pressure sensor was fabricated. The sensitivity of the flexible pressure sensor is about 0.39 kPa−1 at 0–0.5 kPa and 1.04 kPa−1 at 0.5–2.4 kPa, and the response/recovery speed is 75 ms/150 ms, respectively. The fabricated flexible pressure sensor can detect a small pressure of about 6.4 Pa. The experimental results show that the fabricated flexible pressure sensor has high sensitivity, fast response capability, and low detection limit. The flexible pressure sensor for electronic skin demonstrates good performance in the application of finger joint movement and word pronunciation recognition, which indicates that it has great potential application in human motion detection and personal health monitoring. Image 1 • Flexible pressure sensitive unit fabricated by using near-field electrohydrodynamic direct-writing method. • Patterns of flexible pressure sensitive unit were fabricated into a serpentine shape to improve the performance. • The fabricated flexible pressure sensor has high sensitivity, fast response capability, and low detection limit. • The fabricated sensor has good performance in the application of finger joint motion and speech recognition. [ABSTRACT FROM AUTHOR]

As an essential role in electronic skins, flexible pressure sensors have attracted wide attention for their applications in human-machine interaction and intelligent prosthetic, etc. Whereas, in general, it is difficult for most flexible pressure sensors to acquire high accuracy, especially under multi-modal interference (temperature, humidity and deformation). Herein, a novel stretchable flexible pressure sensor was presented by direct writing, which was capable of weakening the strain effect, fending off humidity interference and restraining thermal influence by using a double layer raised island structure substrate, a covering layer and a Wheatstone bridge-configuration of the sensing element. The sensor kept robust under multi-modal interference of strain about 0–20%, temperature of 30–80 °C and humidity in 20–90%, owning high and stable sensitivity of 2.6 kPa−1–14.05 kPa−1 under 0–74 kPa. Two demonstrations of grabbing a bottle with different temperatures and a kid's catching behavior on a opisthenar of a carer verified that such sensor possessed a great potential in many non-structured applications and will be a promising candidate for stretchable flexible pressure sensors in future. Image 1 • A robust pressure sensor which can restrain the interference of deformation, temperature and humidity was presented. • A double layer raised island structure substrate was used to weaken the strain effect. • A Wheatstone bridge configuration of four same sensing elements was elaborated to eliminate the thermal impact. • Two applications including grabbing a bottle and a kid's catching behavior have been demonstrated. [ABSTRACT FROM AUTHOR]

Electronic skin (e-skin), which is an electronic surrogate of human skin, aims to recreate the multifunctionality of skin by using sensing units to detect multiple stimuli, while keeping key features of skin such as low thickness, stretchability, flexibility, and conformability. One of the most important stimuli to be detected is pressure due to its relevance in a plethora of applications, from health monitoring to functional prosthesis, robotics, and human-machine-interfaces (HMI). The performance of these e-skin pressure sensors is tailored, typically through micro-structuring techniques (such as photolithography, unconventional molds, incorporation of naturally micro-structured materials, laser engraving, amongst others) to achieve high sensitivities (commonly above 1 kPa−1), which is mostly relevant for health monitoring applications, or to extend the linearity of the behavior over a larger pressure range (from few Pa to 100 kPa), an important feature for functional prosthesis. Hence, this review intends to give a generalized view over the most relevant highlights in the development and micro-structuring of e-skin pressure sensors, while contributing to update the field with the most recent research. A special emphasis is devoted to the most employed pressure transduction mechanisms, namely capacitance, piezoelectricity, piezoresistivity, and triboelectricity, as well as to materials and novel techniques more recently explored to innovate the field and bring it a step closer to general adoption by society. [ABSTRACT FROM AUTHOR]