Fabrication of Large‐Area Bimodal Sensors by All‐Inkjet‐Printing

Abstract

Electronic skin (e‐skin) is a wearable smart terminal that senses changes of external environment like human skin. It will develop into an indispensable way of interaction between humanity and technology. Here, this bimodal e‐skin that senses bending strain and pressure using an all‐inkjet‐printing method is synthesized. It is based on a microcracked metal film and a sandwich capacitor structure. It is characterized by the metal film of the strain sensor as a bottom electrode of pressure sensor; the electrode plate of the device plays a dual role. When tested, the strain sensor and pressure sensor do not interfere with each other. The device has excellent performance with low pressure‐detection of 2 Pa and high stability over more than 5700 cycles for pressure sensor and high gauge factor (4000) and good stability (over 4500 cycles) for strain sensor, which can recognize the radius of curvature of human activities and objects, and can detect the pressure distribution and the curvature of irregular surfaces, showing its potential applications in wearable devices.

Advanced Soft Materials, Sensor Integrations, and Applications of Wearable Flexible Hybrid Electronics in Healthcare, Energy, and Environment

“…Recently, a large-area strain sensor with high GF (4000) and great stability (over 4500 cycles) was obtained via an all-inkjet printing method (Figure 12a). [293] A microcracked Ag film was sandwiched by capacitor combined with PEN film, Ecoflex, and paper, as a flexible and hydrophilic substrate, encapsulating layer, and soaking layer, respectively. Consequently, the sensing array containing 4 × 4 pixels was obtained via maskless inkjet printing, enabling the spatial mapping of strain and pressure distribution.…”

Advanced Nanomaterials, Printing Processes, and Applications for Flexible Hybrid Electronics

“…The pressure sensor has a sensitivity of 4.2 kPa −1 , the fast response time (<26 ms), and the low detection limit (1.6 Pa). An all-inkjet-printed, bimodal sensor that can measure pressure and strain simultaneously was reported ( Figure 10 f) [ 24 ]. AgNPs suspension was used as a conductive ink.…”

“…Applications for Flexible Hybrid Electronics: Pressure sensor. Reproduced with permission from reference [ 24 ], Copyright 2019, John Wiley and Sons. Temperature sensor.…”

“…Reprinted with permission from reference [ 57 ], Copyright 2018, John Wiley and Sons; ( f ) an image of the sensor array pressed by 10 cylinders with N-shaped and the corresponding capacitance signals of the 16 pixels. Reprinted with permission from reference [ 24 ], Copyright 2019, John Wiley and Sons; ( g ) a skin-like electrode with an open-mesh structure; ( h ) control of machines via classified EEG signals, including a wireless electric wheelchair with five classes (no action, forward, rotate anticlockwise (ACW), rotate clockwise (CW) and reverse), a wireless vehicle with the same commands as the wheelchair. Reproduced with permission from reference [ 29 ], Copyright 2019, Springer Nature; ( i ) an image of printed AgNW dry electrocardiogram (ECG) electrodes and ECG signals collected from the electrode.…”

A Multisensory Tactile System for Robotic Hands to Recognize Objects

“…With the remarkable development of flexible electronics and materials in recent years, flexible sensors and artificial skins with the capability to perceive stimuli have been proposed for robots and prosthesis tactile sensing system, which are based on various sensing principles, such as optoelectronic, piezoresistive, capacitive, thermoresistive, magnetic, triboelectric, or piezoelectric transductions. In addition, emerging liquid metals, conductive fabrics, and inkjet printing technologies have been used to construct large‐area sophisticated sensors with potentials for use in robotic tactile sensing systems.…”