Highly Stretchable, Hysteresis-Free Ionic Liquid-Based Strain Sensor for Precise Human Motion Monitoring

Abstract

A highly stretchable, low-cost strain sensor was successfully prepared using an extremely cost-effective ionic liquid of ethylene glycol/sodium chloride. The hysteresis performance of the ionic-liquid-based sensor was able to be improved by introducing a wavy-shaped fluidic channel diminishing the hysteresis by the viscoelastic relaxation of elastomers. From the simulations on visco-hyperelastic behavior of the elastomeric channel, we demonstrated that the wavy structure can offer lower energy dissipation compared to a flat structure under a given deformation. The resistance response of the ionic-liquid-based wavy (ILBW) sensor was fairly deterministic with no hysteresis, and it was well-matched to the theoretically estimated curves. The ILBW sensors exhibited a low degree of hysteresis (0.15% at 250%), low overshoot (1.7% at 150% strain), and outstanding durability (3000 cycles at 300% strain). The ILBW sensor has excellent potential for use in precise and quantitative strain detections in various areas, such as human motion monitoring, healthcare, virtual reality, and smart clothes.

Ionic Tactile Sensors for Emerging Human‐Interactive Technologies: A Review of Recent Progress

“…b) IL‐based strain‐sensitive ITS with wavy structured microchannels: i) Schematic illustration of the fabrication process; ii) Images of wavy structured Ecoflex 00‐50 under a uniaxial tensile strain of 300%; iii) Monitoring of various human joint motions in real time. Reproduced with permission . Copyright 2016, American Chemical Society.…”

“…These wearable sensors provided accurate and hysteresis‐free strain measurements under both static and dynamic operating conditions. Further, Choi et al fabricated IL‐based wavy sensors (Figure bi) that can show excellent stretchability (up to 250% strain, (Figure bii) and improved hysteresis performance compared to IL‐based flat strain sensors . The wavy structures were found to offer lower energy dissipation compared to the flat structures under a given deformation.…”

1-D polymer ternary composites: Understanding materials interaction, percolation behaviors and mechanism toward ultra-high stretchable and super-sensitive strain sensors

“…Conversely, the stretchable strain sensors have been also reported using ultrathin gold nanowires and carbon nanomaterials, which exhibit wide work range (>100%) but limited sensitivity (GF<10) [7,8]. In addition to high sensitivity and stretchability, the dynamic durability is also an important characteristic index for flexible sensors [9,10]. In most cases, the deterioration of durability is relevant to the irreversible deformation of the flexible matrix, the fracture of conductive network and weak interaction between polymer and conductive fillers [11][12][13].…”

Versatile Method for the Simultaneous Synthesis of Two Ionic Liquids, Otherwise Difficult to Obtain, with High Atom Economy

“…Moreover, they are highly polar and, most importantly, can be recycled. [5] Due to their special properties they can be used in a variety of applications, such as: catalysis, [6][7][8][9] electrochemical sensors, [10] plant systemic acquired resistance inducers, [11] batteries, [12,13] solar cells, [14] supercapacitors, [15] lubricants, [16] gas separation, [17] robotics, [18] drug delivery, [19] biomass conversion, [20] coatings [21] and many more.…”