1D Nanomaterial‐Based Highly Stretchable Strain Sensors for Human Movement Monitoring and Human–Robotic Interactive Systems

Abstract

variety of flexible electronic devices such as tattoo-like sensory skin patches, [1-3] energy harvesters, [4] energy storage elements, [5,6] stretchable interconnects. [7] The astonishing progress in the technologies mentioned above have enabled a new technological drive called "Internet-of-Medical-Things (IoMT)," linking wearable devices/ sensors into a communication network for real-time or periodic patient-doctor communications. [8] The IoMT will help people to better monitor their health status by collecting subtle vital signs modifications and transferring to healthcare service providers. Part of the ongoing research efforts to develop IoMT is focused on the development of wearable sensors that can be embedded in clothing, [9-11] wrist watches, patches [12] and bands, [13-16] contact lenses, [17-21] tattoo-like sensory skin patches (electronic skin), [2,22] etc. to enable around-the-clock vital signs monitoring, human-machine interactive systems, [2] and as bionic ligaments in soft robotics. [23] Among various types of wearable mechanical sensors such as piezoresistive, piezoelectric, and capacitive, the piezoresistive-based strain sensors are gaining a lot of interest as they provide high sensitivity with simple device design and readout circuits [24-30] for vital signs monitoring and soft robotics. Piezoresistive strain sensors are based on the change of electrical properties of the material when subjected to mechanical deformation. Piezoresistive This paper describes a facile strategy of micromolding-in-capillary process to fabricate stretchable strain sensors wherein, the sensing material is wrapped within silicone rubber (Dragon Skin [DS]) to form a sandwichlike structure. Two different 1D sensing materials are exploited to fabricate and study strain sensing performance of such device structure, namely multi-walled carbon nanotubes (MWCNTs) and silver nanowires (AgNWs). The fabricated strain sensors using MWCNT exhibits wide sensing range (2-180%), and moderately high sensing performance with outstanding durability (over 6000 cycles). It is found that MWCNT presents a strong straindependent character in the 45-120% elongation regime. On the other hand, very high gauge factor of >10 6 is achieved using AgNWs at 30% strain with good stability (over 100 cycles). Sensing mechanisms for both 1D conductive sensing materials are discussed. They can be applied for human motion monitoring such as finger, knee, and wrist bending movements to enable human physiological parameters to be registered and analyzed continuously. They are also employed in multichannel and interactive electronic system to be used as a control mechanism for teleoperation for robotic end-effectors. The developed sensors have potential applications in health diagnosis and human-machine interaction.

V2O5 nanowires coated yarn based temperature sensor for smart textiles

“…Flexible and wearable electronics have potential to enhance the quality of human lives by enabling advances in next-generation technologies such as soft robotics, high performance transistors, electronic-skin, interactive objects, energy storage devices, and mobile healthcare etc [1][2][3][4][5][6][7][8][9][10][11]. Among various configurations, the electronic devices in fibre form factors or on textiles could revolutionise the next generation of applications such as mobile healthcare, internet of things etc.…”

Finite element analysis of stress distribution in soft sensors under torsional loading

“…The stretchable strain sensors were fabricated using micromolding-in-capillary process. The details for the process are described elsewhere [32]. The resistive sensing channel is a nanocomposite of multiwalled carbon nanotubes (MWCNTs) and Ecoflex polymer.…”

Multi-Walled Carbon Nanotubes-Based Sensors for Strain Sensing Applications

“…A similar work conducted recently can be seen in [ 114 ], where the authors used a facile strategy to develop highly stretchable strain sensors for monitoring human movements and human–robotic interactive systems. The sensors were fabricated using the micro molding-in-capillary process, where silicon rubber was used to wrap the sensing material to form a sandwich-like structure.…”