A Fully Printed Flexible Sensor Sheet for Simultaneous Proximity–Pressure–Temperature Detection

Abstract

or proximity sensor [7] have been widely applied in safe human-machine interac tion, [8] environmental monitoring, [9] and healthcare management. [10] Unlike conventional sensor platforms that deliver one or two sensing function alities by separate devices, multimodal sensors endeavor to integrate multiple physical or chemical perceptions into a single device, and thus endow individuals with superior intelligence and interac tivity. [11] For instance, Jung et al. demon strated a flexible sensor array capable of detecting pressure and temperature based on piezoresistive and thermoelectric effects, respectively. [12] Temperature and pressure sensing arrays are separated by an insulating film to ensure independent measurements. Similar functions were achieved in a more delicate fingertip shaped resistive sensor, [13] where mate rial tuning and strain isolation reduced coupling between measured variables. To further promote the versatility of sensors, Zhao et al. integrated strain, pressure, and proximity percep tions into a stretchable capacitor array, realizing contact and noncontact interactions. [14] In addition, multiple sensory modal ities were also applied in plant growth management. Takei et al. proposed a flexible sensor sheet mainly based on ZnIn 2 S 4 nanosheets for optical, humidity, and temperature measure ments. [15] Nevertheless, additional efforts should be made to bypass relatively complicated fabrications accompanied by intri cate 3D structures. [13,14,16,17] Printing methods are considered as a versatile category of fabrication technologies to realize functional flexible elec tronics, including screen printing, inkjet printing and dispenser printing, etc. Their merits of customized prototyping, facile manufacturing steps and scalable fabrication [18,19] are prom ising to overcome the sophisticated fabrications for multimodal sensors. Besides, most printing technologies rely on human friendly functional inks rather than hazard chemicals [20,21] (e.g., photoresists or etchants in photolithography). Therefore, the printingbased scheme is environmentfriendly and has the potential to massively produce intelligent multimodal sensors for daily applications.To extend the functionality of multimodal sensors while maintaining facile fabrication processes and overall perfor mance after integration, a trimodal sensor sheet that can be fully manufactured by printing technologies is proposed. It integrates 4 × 4 pressure sensor units, 2 × 2 temperature sensor Flexible multimodal sensors are an indispensable part of Internet of Things for human-machine interfaces, health monitoring, and soft robots. Despite tremendous research efforts dedicated to high sensitivity, flexibility, and multifunctionality, these merits are conventionally accompanied with sophisticated fabrications that hinder practical applications. Herein, a fully printed flexible trimodal sensor sheet containing 4 × 4 pressure sensor units, 2 × 2 temperature sensor units, and 1 proximity sensor unit is proposed. Its elaborate structure featured by a...

Recent Advances in Multiresponsive Flexible Sensors towards E‐skin: A Delicate Design for Versatile Sensing

“…[22,61,183] For instance, multipixel and serpentine interconnection have been printed on PET and PI films as electrode layers for a capacitive trimodal flexible sensor illustrated in Figure 16C. [257] Such an interesting electrode and circuit design enable the fabrication of wearable and stretchable devices, while it increases the sensing unit size and volume to some extent if without careful control of the micro-/nano-structure printing accuracy. Therefore, only a small amount of delicately designed sensing circuits, such as flexible/stretchable electrodes and printed circuits, have been seen to improve the compactness and wearability of flexible sensing devices.…”

“…Reproduced with permission. [257] Copyright 2021, Wiley-VCH. D) Printed circuit and stretchable electrodes in the multifunctional sensing film.…”

“…C) Printed multi-array and serpentine interconnection integrated into the multilayer trimodal sensing system. Reproduced with permission [257]. Copyright 2021, Wiley-VCH.…”

Bioinspired Co‐Design of Tactile Sensor and Deep Learning Algorithm for Human–Robot Interaction

“…To bridge the gap between single‐unit sensing and large‐area sensing, significant efforts have been devoted to developing array‐type bionic sensors, with sensing mechanisms ranging from capacitance, [ 12,13 ] and piezoresistance, [ 14 ] to optics, [ 15 ] and magnetism. [ 16 ] Their lattice arrangements of small‐sized sensing elements on a deformable substrate are proposed to acquire large‐area scalability and distributed sensing capability without losing mechanical compliance.…”

“…[9,10] However, deploying bionic skins onto a large-area surface of the robot is challenging due to the calibrations of numerous sensor units and the lack of algorithm-sensor co-design for intelligent tactile sensing. [11] To bridge the gap between single-unit sensing and large-area sensing, significant efforts have been devoted to developing array-type bionic sensors, with sensing mechanisms ranging from capacitance, [12,13] and piezoresistance, [14] to optics, [15] and magnetism. [16] Their lattice arrangements of small-sized sensing Robots equipped with bionic skins for enhancing the robot perception capability are increasingly deployed in wide applications ranging from healthcare to industry.…”