Recent advances in flexible force sensors and their applications: a review

Abstract

In this paper, five sensing mechanisms including capacitive, piezoresistive, inductive, piezoelectric, and optical are reviewed in details with representative literature. Basic functions of normal force, shear force, shear angle, torsional angle, rotational angle; and characteristics in sensitivity, dynamic window, and spatial resolution are discussed and categorized clearly in this article. In addition, materials used in the flexible force sensors for electrodes, substrates, and deformable dielectrics are highlighted and summarized. Furthermore, structural design, specifications of sensitivity, spatial resolution, dynamic range and cyclic life are also unambiguously outlined. Meanwhile, key design considerations are listed and evaluated in this review to indicate major contributions to the characteristics of the flexible force sensors. Notable challenges, potential business, and examples commercial players in the market are listed at the end of this manuscript. This article offers a stepping stone for those who plan to enter the flexible force sensor fields by revisiting the outcomes from the past decades.

Highly Sensitive Paper-Based Force Sensors with Natural Micro-Nanostructure Sensitive Element

“…Flexible force sensors have important potential applications in fields such as healthcare wearables, artificial intelligence, the Internet of Things, portable electronics, and interactive robots [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ], and have become one of the hot research topics currently. Although the sensing principles and materials used in flexible force sensors vary across studies, they typically include two key components: a sensitive element and a flexible substrate [ 8 , 9 , 10 ]. The flexible force sensors have many advantages, such as high sensitivity, small size, and good flexibility, but there are still some challenges with these two components: (1) The sensitive element, being the most crucial part of flexible force sensors, often employs novel nanomaterials like carbon nanotubes, graphene, metal oxide semiconductors, nanowires, and nanoparticles [ 11 , 12 , 13 , 14 , 15 , 16 , 17 ] to achieve high sensitivity.…”

Highly Sensitive Flexible Pressure Sensors with Hybrid Microstructures Similar to Volcano Sponge

“…In recent years, there has been a growing demand for flexible pressure sensors in the fields of medical monitoring, personalized healthcare, and robotics. – Based on their working principles, flexible pressure sensors can be classified into piezoresistive, – piezocapacitive, , piezoelectric, , and friction-based , sensors. Compared with other types of sensors, piezoresistive sensors have the advantages of low cost, simple structure, and easy signal reading, which are widely used in human motion monitoring and wearable electronics. – Sensitivity and measuring range are the key attributes of flexible pressure sensors.…”

A review on 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene based organic thin film transistor

“…Over many years, OSC materials, as well as OTFT device architectures, have been investigated, and their applications have been significantly explored in several review articles [13][14][15][16][17][18][19][20][21][22]. The geometry of the four most common OTFTs are (1) bottom-gate, bottomcontact; (2) bottom-gate, top-contact (BGTC); (3) top-gate, bottom-contact; and (4) top-gate, topcontact.…”