Wearable Multi-Functional Sensing Technology for Healthcare Smart Detection

Abstract

In recent years, considerable research efforts have been devoted to the development of wearable multi-functional sensing technology to fulfill the requirements of healthcare smart detection, and much progress has been achieved. Due to the appealing characteristics of flexibility, stretchability and long-term stability, the sensors have been used in a wide range of applications, such as respiration monitoring, pulse wave detection, gait pattern analysis, etc. Wearable sensors based on single mechanisms are usually capable of sensing only one physiological or motion signal. In order to measure, record and analyze comprehensive physical conditions, it is indispensable to explore the wearable sensors based on hybrid mechanisms and realize the integration of multiple smart functions. Herein, we have summarized various working mechanisms (resistive, capacitive, triboelectric, piezoelectric, thermo-electric, pyroelectric) and hybrid mechanisms that are incorporated into wearable sensors. More importantly, to make wearable sensors work persistently, it is meaningful to combine flexible power units and wearable sensors and form a self-powered system. This article also emphasizes the utility of self-powered wearable sensors from the perspective of mechanisms, and gives applications. Furthermore, we discuss the emerging materials and structures that are applied to achieve high sensitivity. In the end, we present perspectives on the outlooks of wearable multi-functional sensing technology.

Recent Advances in Touch Sensors for Flexible Wearable Devices

“…Yang et al synthesized a PDA@BTO/PVDF composite by introducing polydopamine (PDA) as a surface modification agent to barium titanate (BaTiO 3 , BTO), followed by their blending with a poly(vinylidene fluoride) (PVDF) matrix [32]. Piezoelectric sensors are commonly used for detecting various human body signals, including respiratory patterns, pulse signals, or recording finger movements [33], and to obtain heart rate signals [33].…”

“…Another component based on triboelectric and resistive integration mechanisms was investigated to detect gestures of prosthesis motion or robotic motion and of the human body [33]. Static and dynamic gestures are detected on the basis of differences in the activity of these integrative principles.…”

“…Figure 4c shows PVDF nanowires in a PDMS film used as a triboelectric layer, along with a piezoelectric and pyroelectric layer developed using polarized PVDF and indium tin oxide-based electrodes, respectively [51]. These generators produce various forms of energy that can be efficiently used to operate multifunctional wearable sensors [33]. In summary, the hybrid mechanism involving the core working structure of wearable devices plays an important role in imparting multifunctionality and in miniaturizing wearable devices, enabling the development of accurate and highly reliable sensors in wearable devices and other healthcare detection kits.…”

Leveraging IoT-Aware Technologies and AI Techniques for Real-Time Critical Healthcare Applications

“…The usage of flexible sensors can fulfil NFR3 and facilitate the development of comfortable and reliable wearable devices suitable for long-term surveillance of critical parameters in prevention, diagnosis, and rehabilitation use cases in the healthcare domain. Adopting advanced miniature flexible skin-compatible sensor technologies also introduces the possibility of accurately monitoring tiny physiological parameters that are usually imperceptible using the typical commercial, wearable devices [ 35 ], thus increasing the chances of fulfilling NFR1. Incorporating multiple sensors also allows the system to gather valuable correlating data that can be used to make more complex and meaningful deductions, thus making wearable-based IoT-aware healthcare frameworks more robust and trustworthy.…”

“…A reference for some healthcare application-specific sensor combinations is available in a survey published by Sabry et al in [ 34 ]. Consequently, adopting miniature, flexible, skin-compatible sensor technology introduces the possibility of unobtrusively monitoring physiological parameters that are usually imperceptible using the typical, commercially available wearable devices [ 35 ]. Ultimately, this allows the definition, design, and development of IoT-based healthcare frameworks that facilitate the long-term surveillance of critical parameters in prevention, diagnosis, and rehabilitation.…”