3D‐Printed Stacked Ionic Assemblies for Iontronic Touch Sensors

Abstract

Sensing is the process of detecting and monitoring any physico-chemical environmental parameters. Herein, new self-powered iontronic sensors, which utilize touch-induced ionic charge separation in ionically conductive hydrogels, are introduced for potential use in object mapping, recognition, and localization. This is accomplished using high-resolution stereolithography (SLA) 3D printing of stacked ionic assemblies consisting of discrete compartments having different ion transport properties. The latter assemblies readily allow programming the output voltage magnitude and polarity by means of variations in ion type, charge density, and cross-linking density within the iontronic device. Voltages of up to 70 mV are generated on application of compressive strains of as much as 50% (≈22.5 kPa), with the magnitude directly proportional to stress, and the polarity dependent on the sign of the mobile ion. As a proof-of-concept demonstration, the resulting touch sensors are integrated on the fingertip to enable the tactile feedback, mimicking the tactile perception of objects for recognition applications. In addition, it is proposed that streaming potential is the underlying mechanism behind the iontronic touch sensors. The electromechanical response is therein consistent with a streaming potential model.

Piezoionic SnSe Nanosheets‐Double Network Hydrogel for Self‐Powered Strain Sensing and Energy Harvesting

“…[5] Last year, Dobashi et al [6] investigated pressure-induced ionic current in a polyacrylamide hydrogel, this phenomenon is called piezoionic effect, [7] referring to ionic soft materials that can generate electrical output under pressure. [8] Recently, Odent et al [9] reported a 3D-printed stacked hydrogel shows large piezoionic output. This effect provides a new idea for the development of highly sensitive hydrogel sensors.…”

“…[ 8 ] Recently, Odent et al. [ 9 ] reported a 3D‐printed stacked hydrogel shows large piezoionic output. This effect provides a new idea for the development of highly sensitive hydrogel sensors.…”

Perspectives on recent advancements in energy harvesting, sensing and bio-medical applications of piezoelectric gels

“…250–252 Hydrogels have recently gained significant attention in the domain of artificial skin due to their resemblance to human tissues, since these materials are soft, high-water content, flexible, wearable and show high biocompatibility. 253–255 The majority of hydrogel-based sensors are piezoresistive, based on the principle that the electrical resistivity of a material changes when mechanical strain is applied. 256–258 However, piezoresistive hydrogels show several disadvantages, including an apparent hysteresis effect, low mechanical durability, ease of temperature variations, and the prerequisite for an external source of power, which pose significant barriers to practical application.…”

Iontronic memories based on ionic redox systems: operation protocols

“…Recently ionic systems have been broadly investigated due to the increased demand for neuromorphic applications, new computing methods, and less energy consumption 2 . Different iontronic devices based on the concept of transmitting, generating or storing signals by ions were developed in the last years [3][4][5][6][7][8][9][10][11][12] . The electric double layer (EDL) formation at the interface between two different materials is considered one of the important processes in iontronics.…”