Bioinspired Design of Hill‐Ridge Architecture‐Based Iontronic Sensor with High Sensibility and Piecewise Linearity

Abstract

Flexible pressure sensors can by further classified into four general types based on the mechanisms: resistive, [3][4][5][6] capacitive, [7][8][9][10][11][12] piezoelectric, and triboelectric [13][14][15][16][17][18] type. Particularly, capacitive sensors are quite attractive due to their low power consumption and fast response time. However the confined electrode distance restricted its sensitivity, making it subject to parasitic charges and environmental electromagnetic noises. [19] In 2011, Pan's group originally demonstrated a new sensing mechanism, known as iontronic sensing. [20] Owing to the supercapacitive nature of the electrical double layer (EDL), the values order of unit area capacitance (UAC) could rocket from pF cm -2 to nF cm -2 even μF cm -2 , therefore the novel iontronic sensors usually show a much higher sensitivity compared with traditional capacitive sensors. [21][22][23][24][25][26][27][28][29][30][31] Despite significant progress in improving sensitivity, linear and wide detection range is still highly desirable in many applications. [32] To improve linear sensing performance, different structural designs have been proposed. For instance, hierarchical and multilayer structure provide linear output for resistive sensors; [33][34][35] linear response of capacitive sensors was achieved by regulating the dielectric constant variation with deformation. [36] However, these methods cannot be applied directly to iontronic sensors due to their disparate sensing mechanisms. Analogous strategies suitable for iontronic sensors yet still need to be studied. Furthermore, in a defined dynamic range, high sensitivity in the beginning consumes a major deformation and thus the sensing range is limited. Conversely, a sensor with wide sensing range can hardly detect slight pressure. Therefore, it is still a challenge to balance the sensitivity and wide sensing-range. Coincidentally, nature has already provided the answer. Evolving through natural selection, insects have evolved a variety of adaptations to adapt to different habitats. To adapt the environmental stimuli with several orders of magnitude, different receptors are employed to perceive slight and big pressure respectively. For instance, the insect organs used for mechanical transduction can be morphologically divided into tactile hairs and campaniform sensilla. [37] Different structures are used to detect different magnitudes of forces to achieve corresponding functions. Figure 1a shows the microstructures of mechanoreceptors of a parasitoid fly. As

A bio-inspired tactile nociceptor constructed by integrating wearable sensing paper and a VO2threshold switching memristor

“…We have previously presented work on AgNW/PVA/H 3 PO 4 hydrogel electrodes. 28 Finally, the E-skin was edge-packaged with a 3M tape while conductive tape was utilized as wires.…”

Recent Advances of Capacitive Sensors: Materials, Microstructure Designs, Applications, and Opportunities

“…Recently, to further improve the sensitivity of capacitive pressure sensors, the dielectric material in middle layer of the sensor have been replaced by ionic gel-based materials to form electric double layer (EDL) capacitance, becoming supercapacitive sensors with ultrahigh sensitivity. [48,49] Capacitive temperature sensors [50][51][52][53][54] exhibit great potential to be applied in anti-icing systems, [55] body temperature measurement, and hightemperature chemical reaction monitoring. In recent, to improve the sensing performance of temperature sensor, ionic material is used to improve the performance of temperature sensor, [56,57] and the structure like kirigami was introduced, [58] contributing toward the enhancement of sensitivity and stretchability.…”

Multifunctional Iontronic Sensor Based on Liquid Metal-Filled Ho llow Ionogel Fibers in Detecting Pressure, Temperature, and Proximity

“…In the past decade, a new type of capacitive pressure sensor called “iontronic sensor” with an ion-conductive film as the dielectric layer has emerged, which can dramatically enhance the signal of the outputted capacitance. − Inside the iontronic sensor, the electric double layer (EDL) can be formed at the interface between the ionic layer and the electrode layer, thus leading to the superior sensitivity and high unit area capacitance (UAC). − The enhanced UAC helps improve the detection resolution and noise immunity of the sensor. , For instance, Guo et al reported a film-shaped iontronic pressure sensor with interfacial EDL, in which microstructures with various heights on the ionic film were designed to improve structural compressibility of the fabricated sensor. A high sensitivity (220–3300 kPa –1 ), high-pressure resolution (10 Pa), and wide pressure range (up to 360 kPa) were achieved simultaneously for this sensor owing to the ingenious design in microstructures.…”