Lightweight Wearable Devices Research Articles

A stretchable breathable washable all-textile smart wearable keyboard

The development of comfortable and lightweight wearable devices is an emerging technological goal in human-computer interaction. Conductive textiles attract a great deal of interest as versatile materials for wearable devices. It can naturally integrate into our daily clothing, making wearable devices more comfortable and convenient. However, developing all-textile wearable devices remains an important challenge. And the wiring of wearable devices in practical applications is also a thorny issue. In this study, a novel wearable smart keyboard is proposed. Benefit from the ingenious structural design of double-faced effect functional textiles and 3D spacer textiles, the smart keyboard achieves all-textile structure and the wires can also be hidden inside the 3D spacer textile. The smart keyboard is stretchable, breathable, washable and can be integrated with daily clothing by sewing. In addition to the functions of traditional keyboards, smart keyboards also have the ability to detect tapping force which lays the foundation for future intelligent applications, such as tracking the tapping force of typewriting to enhance security.The application examples of integrating the smart keyboard into lab-coat for typewriting are demonstrated. This study shows that the novel smart keyboard has great potential in the fields of wearable devices and human-computer interface.

Lightweight polyurethane composite foam for electromagnetic interference shielding with high absorption characteristic

Due to the rapid growth of electronic equipment technology, efficient electromagnetic shielding materials are needed for equipment and human protection. Among them, foam shielding materials with absorption as the primary mechanism have higher application value than highly reflective materials. Highly absorbing shielding materials can reduce the secondary pollution caused by electromagnetic wave reflection. In this study, we added Fe3O4@Polyvinyl alcohol (Fe3O4@PVA) and graphene oxide@silver (GO@Ag) into the polyurethane (PU) matrix and constructed Fe3O4@PVA and GO@Ag/PU composite foam by foaming. Fe3O4@PVA and GO@Ag form an excellent network structure in the PU foam skeleton, significantly improving its electromagnetic shielding effectiveness (EMI SE) and mechanical properties. The shielding effectiveness reached 30.9 dB with a specific EMI SE (SSE) of 274.9 dB × cm3 × g−1 at a Fe3O4@PVA filling of 7 wt%, where the electromagnetic wave absorption accounted for more than 80 % of the total EMI SE, proving absorption as the primary shielding mechanism. The results show that Fe3O4, as a ferromagnet, has both the dielectric loss of ferroelectric materials and the hysteresis loss of ferromagnetic materials in electromagnetic shielding, effectively improving the wave absorption performance of composite shielding materials. Therefore, this work provides a promising idea for efficient and lightweight wave-absorbing shielding materials in aerospace, portable electronic devices and lightweight wearable devices.

94 Reducing Exposure to Respirable Crystalline Silica in the Construction and Minerals Industry by Using Wearable Real Time Respirable Dust Monitors

Abstract Real time monitoring of respirable dust (as a surrogate for RCS) opens the opportunity to warn workers when entering work areas with increased dust levels to provide them the information to fit RPE properly or exit the area. However in the past, the adoption of such monitoring approaches has been limited due to the bulkiness and price of devices. This paper reflects on how the miniaturisation of Optical Particle Counters has enabled light weight (<150g) wearable devices to be developed which are convenient for workers in the construction and minerals industry to wear on all working days. It provides an overview of the Optical particle counter. its performance in measuring respirable dust and how it has been integrated into a battery powered ' DustCanary; wearable device. Due to its size and convenience the DustCanary provides protection to both those at first line risk due to the areas they work (eg stone cutters, plant operatives) who by wearing such can devices can help identify changes in performance of Local Exhaust Ventilation (LEV). or controls so that remedial action can be taken secondary risk on a plant who are not necessarily wearing RPE (such as delivery drivers) who can be warned when they enter an area where there are elevated respirable dust levels Case study data and examples will be shared.

Communicating the Urban Experience through Biosensing: A Participatory Approach

Advances in biosensing technologies have led to the commercialization of novel lightweight wearable devices, which have been praised by urban scholars for offering the possibility to quantify emotions in real-world settings, something that had proven to be very challenging until now. Although many studies mix biosensing with qualitative methods to provide a clearer picture of what physiological data might mean in terms of emotions, there has been little exploration of how people interpret their own biodata. Following calls for greater attention to participation in biosensing studies, this article explores the nuances of the interpretation of biodata by research participants. Drawing on the findings of a study in which participants were invited to reflect on and discuss their own biodata during and after a walk in a high street in Lisbon, we show how exposing participants to biodata creates moments of bounded interference that foster in-depth reflection about the urban experience. With this in mind, we discuss how bounded interference can be a generative driver for more detailed discussions about spatial experiences.

Dual-Branch Interactive Networks on Multichannel Time Series for Human Activity Recognition.

The popularity of convolutional architecture has made sensor-based human activity recognition (HAR) become one primary beneficiary. By simply superimposing multiple convolution layers, the local features can be effectively captured from multi-channel time series sensor data, which could output high-performance activity prediction results. On the other hand, recent years have witnessed great success of Transformer model, which uses powerful self-attention mechanism to handle long-range sequence modeling tasks, hence avoiding the shortcoming of local feature representations caused by convolutional neural networks (CNNs). In this paper, we seek to combine the merits of CNN and Transformer to model multi-channel time series sensor data, which might provide compelling recognition performance with fewer parameters and FLOPs based on lightweight wearable devices. To this end, we propose a new Dual-branch Interactive Network (DIN) that inherits the advantages from both CNN and Transformer to handle multi-channel time series for HAR. Specifically, the proposed framework utilizes two-stream architecture to disentangle local and global features by performing conv-embedding and patch-embedding, where a co-attention mechanism is used to adaptively fuse global-to-local and local-to-global feature representations. We perform extensive experiments on three mainstream HAR benchmark datasets including PAMAP2, WISDM, and OPPORTUNITY, which verify that our method consistently outperforms several state-of-the-art baselines, reaching an F1-score of 92.05%, 98.17%, and 91.55% respectively with fewer parameters and FLOPs. In addition, the practical execution time is validated on an embedded Raspberry Pi P3 system, which demonstrates that our approach is adequately efficient for real-time HAR implementations and deserves as a better alternative in ubiquitous HAR computing scenario. Our model code will be released soon.

Joint neural phase retrieval and compression for energy- and computation-efficient holography on the edge

Recent deep learning approaches have shown remarkable promise to enable high fidelity holographic displays. However, lightweight wearable display devices cannot afford the computation demand and energy consumption for hologram generation due to the limited onboard compute capability and battery life. On the other hand, if the computation is conducted entirely remotely on a cloud server, transmitting lossless hologram data is not only challenging but also result in prohibitively high latency and storage. In this work, by distributing the computation and optimizing the transmission, we propose the first framework that jointly generates and compresses high-quality phase-only holograms. Specifically, our framework asymmetrically separates the hologram generation process into high-compute remote encoding (on the server), and low-compute decoding (on the edge) stages. Our encoding enables light weight latent space data, thus faster and efficient transmission to the edge device. With our framework, we observed a reduction of 76% computation and consequently 83% in energy cost on edge devices, compared to the existing hologram generation methods. Our framework is robust to transmission and decoding errors, and approach high image fidelity for as low as 2 bits-per-pixel, and further reduced average bit-rates and decoding time for holographic videos.

A Succinct Review on Piezoelectric Characteristics of PVDF and its Copolymer PVDF-HFP

Researchers are making attempts to develop a lightweight, shock resistance, portable, wireless sensors, and flexible wearable electronic devices. Piezoelectric nanogenerators are those which are used to convert mechanical into electrical energy and vice versa, which in turn meets the requirement of low-powered electronic gadgets. PVDF (Poly vinylidene difluoride) is found to be one of the versatile polymeric materials with intriguing characteristics and many technological applications. In recent days, Polyvinylidene difluoride and its copolymers like P(VDF-trifluoroethylene) and P(VDF-tetrafluoroethylene) are being explored extensively in order to produce energy harvesting devices. The present study deals with recent trends in the processing techniques of piezoelectric materials PVDF-HFP with different nano fillers in order to enhance its efficiency. This article may inspire several researchers to fabricate polymer composites of PVDF-HFP with different additives, which finds applications in several fields like shoe pad nanogenerator, biomedical, smart scaffolds, spin valve devices, and hybrid generators.

Soft, Lightweight Wearable Robots to Support the Upper Limb in Activities of Daily Living: A Feasibility Study on Chronic Stroke Patients.

Stroke can be a devastating condition that impairs the upper limb and reduces mobility. Wearable robots can aid impaired users by supporting performance of Activities of Daily Living (ADLs). In the past decade, soft devices have become popular due to their inherent malleable and low-weight properties that makes them generally safer and more ergonomic. In this study, we present an improved version of our previously developed gravity-compensating upper limb exosuit and introduce a novel hand exoskeleton. The latter uses 3D-printed structures that are attached to the back of the fingers which prevent undesired hyperextension of joints. We explored the feasibility of using this integrated system in a sample of 10 chronic stroke patients who performed 10 ADLs. We observed a significant reduction of 30.3 ± 3.5% (mean ± standard error), 31.2 ± 3.2% and 14.0 ± 5.1% in the mean muscular activity of the Biceps Brachii (BB), Anterior Deltoid (AD) and Extensor Digitorum Communis muscles, respectively. Additionally, we observed a reduction of 14.0 ± 11.5%, 14.7 ± 6.9% and 12.8 ± 4.4% in the coactivation of the pairs of muscles BB and Triceps Brachii (TB), BB and AD, and TB and Pectoralis Major (PM), respectively, typically associated to pathological muscular synergies, without significant degradation of healthy muscular coactivation. There was also a significant increase of elbow flexion angle ( 12.1±1.5° ). These results further cement the potential of using lightweight wearable devices to assist impaired users.

Lightweight and elastic wood-derived composites for pressure sensing and electromagnetic interference shielding

Due to the rapid development of the wearable flexible electronics industry, the demand for multifunctional materials has greatly increased; however, it is still challenging to apply wearable flexible materials across different applications while ensuring suitable performance. In this study, inspired by the structure and morphology of natural wood, a multi-channel 3D cellulose scaffold (CS) was obtained by delignification. Then, carbon nanotubes (CNTs)/MXene composite nanosheets were inserted into the CS via vacuum impregnation. Finally, a hydrophobic and multifunctional wood-derived composite (CMP/CS) was prepared by wrapping with poly (dimethylsiloxane) (PDMS). The CMP/CS composite possessed a high compressive strength of 1.53 MPa and a maximum strain at fracture of 74.1%, and also exhibited excellent electromagnetic interference (EMI) shielding performance (29.3 dB), meeting the requirements of commercial EMI shielding applications. A constructed CMP/CS sensor exhibited a high gauge factor (3.94) and good cyclic stability (over 1000 cycles) and could monitor various human movements in real-time. The thin PDMS protective layer rendered the CMP/CS composite hydrophobic and improved its durability for daily applications. Thus, this smart wood-derived composite provides a reference for studying next-generation lightweight wearable electronic devices.

Malicious Activity Detection in Lightweight Wearable and IoT Devices Using Signal Stitching.

The integrated circuit (IC) manufacturing process involves many players, from chip/board design and fabrication to firmware design and installation. In today’s global supply chain, any of these steps are prone to interference from rogue players, creating a security risk. Therefore, manufactured devices need to be verified to perform only their intended operations since it is not economically feasible to control the supply chain and use only trusted facilities. This paper presents a detection technique for malicious activity that can stem from hardware or firmware Trojans. The proposed technique relies on (i) repetitious side-channel sample collection of the active device, (ii) time-domain stitching, and (iii) frequency domain analysis. Since finding a trusted sample is generally impractical, the proposed technique is based on self-referencing to remove the effects of environmental or device-to-device variation in the frequency domain. We first observe that the power spectrum of the Trojan activity is confined to a low-frequency band. Then, we exploit this fact to achieve self-referencing using signal detection theory. The proposed technique’s effectiveness is demonstrated through experiments on a wearable electronics prototype and system-on-chip (SoC) under a variety of practical scenarios. Experimental results show the proposed detection technique enables a high overall detection coverage for malicious activities of varying types with 0.8 s monitoring time overhead, which is negligible.

Otariidae-Inspired Soft-Robotic Supernumerary Flippers by Fabric Kirigami and Origami

Wearable robotic devices are receiving rapidly growing attentions for human-centered scenarios from medical, rehabilitation, to industrial applications. Supernumerary robotic limbs have been widely investigated for the augmentation of human limb functions, both as fingers and manipulator arms. Soft robotics offers an alternative approach to conventional motor-driven robot limbs toward safer and lighter systems, while pioneering soft supernumerary limbs are strongly limited in payload and dexterity by the soft robotic design approach, as well as the fabrication techniques. In this article, we proposed a wearable supernumerary soft robot for the human forearm, inspired by the fore flippers of otariids (eared seals). A flat flipper design was adopted, differing from the finger- or arm-shaped state-of-the-art works, with multiple soft actuators embedded as different joints for manipulation dexterity. The soft actuators were designed following origami (paper folding) patterns, reinforced by kirigami (paper cutting) fabrics. With this new approach, the proposed soft flipper incorporated eight independent muscles, achieving over 20 times payload to self-weight ratio, while weighing less than 500 g. The versatility, dexterity, and payload capability were experimentally demonstrated using a fabricated prototype with proprietary actuation and control. This article demonstrates the feasibility and unique advantages of origami + kirigami soft robots as a new approach to strong, dexterous, and yet safe and lightweight wearable robotic devices.

Applications of Light-Weight Wearable Devices to Online Programming of Industrial Dual-Arm Robots

Dexterous manipulation of dual-arm robots in unstructured environments is very useful. Programming a dual-arm industrial robot to efficiently complete dexterous tasks, however, is especially challenging due to the complexity of its inverse kinematics, motion planning, dual-arm coordination with self-collision avoidance, and so on. This paper presents a systematic solution to accurately manipulate a dual-arm industrial robot on-site via light-weight wearable devices. In the developed system, the human operator directly drives the robot through the human arms motions tracked by the combination of inertial measurement units and handheld joystick controllers. A proper motion retargeting method with self-collision avoidance is used to enable the user to manipulate the robot directly through intuitive arm motions within a comfortable range and ensure the task manipulation with safety in unstructured environments. The developed system has been tested with various tasks, such as the manipulation of objects of different shapes, dexterous turn-over, and dual-arm coordination. Compared with the existing telerobotic systems, the developed system with simultaneous 14 degree-of-freedom teleoperation directly driven by light-weight wearable devices is able to handle more dexterous and accurate manipulation tasks with the capability of fast deployment and self-collision awareness. Such a solution could pave the way for online dual-arm robot programming on efficient manipulation skills transfer in the future.

Augmenting Cognition Through Edge Computing

Augmented cognition can transform human capabilities, but delivering its benefits in real time will require low-latency wireless access to powerful infrastructure resources by lightweight wearable devices. Edge computing is the only viable approach to meeting these stringent requirements. We explore the symbiotic relationship between augmented cognition and edge computing.

Printed Organic Circuit Systems for Wearable Lactate Sensors

Wearable sensor devices that enable continuous real-time monitoring and analysis of biological information from the human body are promising in the fields of sports, healthcare, and medical applications. A variety of biomarkers in body fluids (such as perspiration, saliva) can be continuously detected by a wearable electrochemical sensing system, which enables in situ analysis of physiological signals. An enzyme-based amperometric sensor is one of the most important electrochemical sensors owing to the high selectivity and the connectivity to information technologies. So far, the quantitative measurement of metabolites in human fluids, including lactate, glucose, and uric acid, have been carried out using enzyme-based amperometric sensors and conventional potentiostat systems. A potentiostat is the electronic hardware which controls the three-electrode cell for electrochemical experiments and possesses two functions: (1) maintaining the potential of the working electrode (WE) at a constant level with respect to the reference electrode (RE) by adjusting the current at a counter electrode (CE), and (2) converting the current at the working electrode to the voltage by a transimpedance amplifier with a high gain. Hence, both the enzyme-based amperometric sensors and the potentiostat need to be integrated in the wearable devices. Organic thin-film transistors (OTFTs) have potential for realizing ultra-thin, lightweight, and flexible circuit components of the potentiostat for wearable sensor devices owing to their advantages such as the small Young’s modulus, biocompatibility, and the processability of direct printing onto plastic films. Printability is an attraction of OTFTs because organic materials can be dissolved in organic solvents, which enables roll-to-roll manufacture of large-area devices on flexible substrates. These features are significant requirements for making the low-cost devices attachable onto human tissues or clothes like a patch. So far, OTFTs have been utilized as amplifiers for potentiometric electrochemical sensors, which is called extended-gate type OTFTs. Although the potentiometric measurement is applicable to enzymatic sensors, it exhibits an irreversible and slow response in several minutes, which is not suitable to real-time sensing. On the other hand, the amperometric measurement based on enzymatic sensors exhibits a reversible and fast response in several tens of seconds. OTFTs have never been utilized for amperometric sensors since the three-electrode system requires complex integrated circuits rather than the simple extended-gate type OTFTs. In this work, we demonstrate a novel flexible and printed organic circuit system for wearable amperometric electrochemical sensors, implemented with two OTFT-based negative-feedback inverters. The inverters employed pseudo-CMOS design for obtaining rail-to-rail operation and low output impedance, and consisted of the OTFTs based on a blend of a small molecular p-type semiconductor and polystyrene for the active layer. The first inverter was utilized to maintain the potential at the WE at a constant level with respect to the RE. The second inverter was utilized to convert the current at the WE into voltage with a tunable gain of 106–107 V/A. A lactate sensor with a lactate oxidase membrane was used as the WE. This simple system worked like a potentiostat for electrochemical measurements, and enabled the quantitative and real-time measurement of lactate concentration with high sensitivity of 1 V/mM and a short response time of a hundred seconds. These results will allow organic semiconductor devices to have potential for realizing extremely thin and lightweight wearable devices for in situ monitoring of metabolites in body fluids.

Secret Key Establishment via RSS Trajectory Matching Between Wearable Devices

Recently, people have witnessed a remarkable growth in the number of smart wearable devices. Accompanied with the development of a contactless data transmission technique, the lack of effective secret key establishment between lightweight wearable devices which support contactless data transmission technique becomes a security bottleneck. In this paper, we propose a novel wireless key establishment method by moving or shaking the wearable wireless devices. Instead of received signal strength (RSS) itself, we denote the RSS trajectories of two moving wireless devices as the materials of secret key. Moreover, inspired by channel reciprocity in a channel feature-based key establishment technique, we propose the concept of reciprocity of RSS trajectory that guarantees that even when the RSSs of two devices are the same, the identical RSS trajectories of two devices can successfully generate the secret key. In addition, to effectively utilize the RSS trajectories, we design a novel quantization scheme by considering the entropy and efficiency of key generation. Furthermore, we analyze the security of this key establishment procedure in an eavesdropped and monitored environment. We also perform an evaluation of 64-, 128-, 192-, and 256-b key generation in indoor/outdoor environment, and the results indicate that the times are 0.22/0.33, 0.61/0.74, 0.95/1.02, and 1.28/1.46 s, respectively. In addition, the ranges of efficiency and entropy are 0.654-0.795 and 0.968-0.993.

The yoking-proof-based authentication protocol for cloud-assisted wearable devices

Along with the development of IoT applications, wearable devices are becoming popular for monitoring user data to provide intelligent service support. The wearable devices confront severe security issues compared with traditional short-range communications. Due to the limitations of computation capabilities and communication resources, it brings more challenges to design security solutions for the resource-constrained wearable devices in IoT applications. In this work, a yoking-proof-based authentication protocol (YPAP) is proposed for cloud-assisted wearable devices. In the YPAP, a physical unclonable function and lightweight cryptographic operators are jointly applied to realize mutual authentication between a smart phone and two wearable devices, and yoking-proofs are established for the cloud server to perform simultaneous verification. Meanwhile, Rubin logic-based security formal analysis is performed to prove that the YPAP has theoretical design correctness. It indicates that the proposed YPAP is flexible for lightweight wearable devices in IoT applications.

DEVELOPMENT OF AN INEXPENSIVE HEALTH MONITORING SYSTEM FOR THE LONE ELDERLY

This paper proposes the design and implementation of an intelligent health monitoring system, e-Guardian, which helps the elderly live independently and offers peace of mind to their family members. The heart of the system is a base station (BS) that acts as a gateway between GSM/GPRS and WSN. At seniors’ sides are a number of small and lightweight wearable devices (WDs) which are capable of automatically detecting accidental falls, inferring simple activities of daily livings (ADLs), monitoring body temperatures and heart rates, etc. WDs communicate with BS, possibly via range extenders (REs) in several hops. During an emergency, alert signals will be sent to family members or caregivers via SMS. To avoid network congestions, e-Guardian takes a decentralized approach by processing sensor data locally in WDs instead of streaming raw sensor data to the BS for processing. An interrupt-driven fall detection algorithm using a digital microelectromechanical-system (MEMS) accelerometer has been designed to allow host microcontroller units (MCUs) to process data only upon interrupts and sleep the rest of the time, thus achieving several months of standby time. The system consumes minimum bandwidth thus allows its network to scale easily to cover a large area. The scalability allows an e-Guardian system to be deployed in not only households but also care centers, hospitals and even entire village/community areas thus the cost per senior is further reduced.