A metal-electrode-free, fully integrated, soft triboelectric sensor array for self-powered tactile sensing

Abstract

The dramatic advances in flexible/wearable electronics have garnered great attention for touch sensors for practical applications in human health monitoring and human-machine interfaces. Self-powered triboelectric tactile sensors with high sensitivity, reduced crosstalk, and simple processing routes are highly desirable. Herein, we introduce a facile and low-cost fabrication approach for a metal-electrode free, fully integrated, flexible, and self-powered triboelectric tactile sensor array with 8-by-8 sensor units. Through the height difference between the sensor units and interconnect electrodes, the crosstalk derived from the electrodes has been successfully suppressed with no additional shielding layers. The tactile sensor array shows a remarkable sensitivity of 0.063 V kPa-1 with a linear range from 5 to 50 kPa, which covers a broad range of testing objects. Furthermore, due to the advanced mechanical design, the flexible sensor array exhibits great capability of pressure sensing even under a curved state. The voltage responses from the pattern mapping by finger touching demonstrate the uniformity of the sensor array. Finally, real-time tactile sensing associated with light-emitting diode (LED) array lighting demonstrates the potential application of the sensor array in position tracking, self-powered touch screens, human-machine interfaces and many others.

Flexible High‐Resolution Triboelectric Sensor Array Based on Patterned Laser‐Induced Graphene for Self‐Powered Real‐Time Tactile Sensing

“…To reveal the pressure sensitivity of the TSA, the output voltage responding to the pressure was recorded and a pressure sensitivity of 0.016 V kPa –1 was obtained under the pressure lower than 200 kPa (Figure S8, Supporting Information), which is smaller than the reported results of 0.06 V kPa –1 . [ 17,24 ] To evaluate the mechanical flexibility and electrical reliability of the patterned LIG electrodes (radium of 2 mm), the resistance was measured under various mechanical bending conditions. Figure 2e shows the resistance of patterned LIG electrode at different bending angles (0–180 o ) and after 5000 bending cycles (angle of 180 o ) (Figure S9, Supporting Information).…”

“…It is worth noting that the crosstalk is a great challenge problem in TENG‐based tactile sensing arrays when the output is not high enough. [ 35 ] At present, great efforts have been devoted to suppress the crosstalk between sensing pixels as well as the adjacent electrodes, such as adopting a shielding layer [ 33,35,49,50 ] and designing height difference between the sensor units and interconnect electrodes [ 24 ] and sensing unit with patterned subdivision structure. [ 19 ] However, without additional shielding layer, the crosstalk suppression has also been demonstrated from TENG with particular pattern.…”

“…Fortunately, a newly arising triboelectric nanogenerator (TENG) developed by Wang and co‐workers provides a promising solution to address the issue mentioned above. [ 3–7,19–24 ] Based on the sensing mechanism of coupling contact electrification and electrostatic induction, [ 25–30 ] TENG, with intrinsic merits of cost efficiency, high output voltage, easy manufacturability, and zero power consumption, can harvest ambient mechanical energy and convert it into electricity, which can be employed to act directly as self‐powered active sensor. [ 3–5,19,22,24,30–32 ] For instance, Wang et al.…”

“…Recently, a facile, metal‐electrode free, fully integrated, and flexible TSA with 8‐by‐8 sensor units has been reported by Zi group. [ 24 ] Although the crosstalk from the electrodes has been successfully suppressed by special device design, the issues on complicated fabrication, low sensing resolution and tedious wiring layout still need be addressed due to every sensor unit individually connected as one data channel. Therefore, the fabrication usually involves the specialized equipment and sophisticated or expensive processes, such as photolithography, vacuum deposition, etching, and/or other complicated procedures and designs, [ 4,5,21,33–35 ] which are high‐cost and time‐consuming and would block their widespread practical applications.…”

Self-Powered Intelligent Human-Machine Interaction for Handwriting Recognition

“…The triboelectric nanogenerator converts mechanical signals into electrical signals and harvests mechanical energy by storing electrostatic charge, thus serving as ideal devices for recording handwritten signals [ 33 – 35 ]. Generally, self-powered active sensors based on triboelectrification require a digital array configuration (i.e., digital sensing mechanism) to detect mechanical signals [ 36 – 41 ]. A large number of electrodes will introduce difficulties in signal reading and data backend processing.…”