Wearable Design Research Articles

Digital twin driven electrode optimization for wearable bladder monitoring via bioimpedance

Monitoring fluid intake and output for congestive heart failure (CHF) patients is an essential tool to prevent fluid overload, a principal cause of hospital admissions. Addressing this, bladder volume measurement systems utilizing bioimpedance and electrical impedance tomography have been proposed, with limited exploration of continuous monitoring within a wearable design. Advancing this format, we developed a conductivity digital twin from radiological data, where we performed exhaustive simulations to optimize electrode sensitivity on an individual basis. Our optimized placement demonstrated an efficient proof-of-concept volume estimation that required as few as seven measurement frames while maintaining low errors (CI 95% −1.11% to 1.00%) for volumes ≥100 mL. Additionally, we quantify the impact of ascites, a common confounding condition in CHF, on the bioimpedance signal. By improving monitoring technology, we aim to reduce CHF mortality by empowering patients and clinicians with a more thorough understanding of fluid status.

Design, Characterization, and Evaluation of Textile Systems and Coatings for Sports Use: Applications in the Design of High-Thermal Comfort Wearables.

Exposure to high temperatures during indoor and outdoor activities increases the risk of heat-related illness such as cramps, rashes, and heatstroke (HS). Fatal cases of HS are ten times more common than serious cardiac episodes in sporting scenarios, with untreated cases leading to mortality rates as high as 80%. Enhancing thermal comfort can be achieved through heat loss in enclosed spaces and the human body, utilizing heat transfer mechanisms such as radiation, conduction, convection, and evaporation, which do not require initial energy input. Among these, two primary mechanisms are commonly employed in the textile industry to enhance passive cooling: radiation and conduction. The radiation approach encompasses two aspects: (1) reflecting solar spectrum (SS) wavelengths and (2) transmitting and emitting in the atmospheric window (AW). Conduction involves dissipating heat through materials with a high thermal conductivity. Our study focuses on the combined effect of these radiative and conductive approaches to increase thermal energy loss, an area that has not been extensively studied to date. Therefore, the main objective of this project is to develop, characterize, and evaluate a nanocomposite polymeric textile system using electrospinning, incorporating graphene oxide (GO) nanosheets and titanium dioxide nanoparticles (TiO2 NPs) within a recycled polyethylene terephthalate (r-PET) matrix to improve thermal comfort through the dissipation of thermal energy by radiation and conduction. The textile system with a 5:1 molar ratio between TiO2 NPs and GO demonstrates 89.26% reflectance in the SS and 98.40% transmittance/emittance in the AW, correlating to superior cooling performance, with temperatures 20.06 and 1.27 °C lower than skin temperatures outdoors and indoors, respectively. Additionally, the textile exhibits a high thermal conductivity index of 0.66 W/m K, contact angles greater than 120°, and cell viability exceeding 80%. These findings highlight the potential of the engineered textiles in developing high-performance sports cooling fabrics, providing significant advancements in thermal comfort and safety for athletes.

Advancements in wearable heart sounds devices for the monitoring of cardiovascular diseases

AbstractCardiovascular diseases remain a leading global cause of mortality, underscoring the urgent need for intelligent diagnostic tools to enhance early detection, prediction, diagnosis, prevention, treatment, and recovery. This demand has spurred the advancement of wearable and flexible technologies, revolutionizing continuous, noninvasive, and remote heart sound (HS) monitoring—a vital avenue for assessing heart activity. The conventional stethoscope, used to listen to HSs, has limitations in terms of its physical structure, as it is inflexible and bulky, which restricts its prospective applications. Recently, mechanoacoustic sensors have made remarkable advancements, evolving from primitive forms to soft, flexible, and wearable designs. This article provides an in‐depth review of the latest scientific and technological advancements by addressing various topics, including different types of sensors, sensing materials, design principles, denoising techniques, and clinical applications of flexible and wearable HS sensors. This transformative potential lies in the capacity for ongoing, remote, and personalized monitoring, promising enhanced patient outcomes, amplified remote monitoring capabilities, and timely diagnoses. Last, the article highlights current challenges and prospects for the future, suggesting techniques to advance HS sensing technologies for exciting real‐time applications.

A brief report: Lessons learned using wearable technology to collect data from adults receiving medications for opioid use disorder

ABSTRACT Background Incorporating wearable technology into substance use disorder research enables continuous, objective, and remote data collection, facilitating symptom monitoring to prevent relapse. However, implementation challenges may hinder data collection. This paper aims to assess adherence patterns to a wrist-worn wearable device, and to share lessons learned from incorporating wearable technology to collect physiological data from adults with opioid use disorder. Methods Employing a prospective observational design, we used convenience sampling to recruit adults receiving medications for opioid use disorder in outpatient settings. Wearable adherence was measured by days and nights worn over eight weeks, acceptability by a visual analog scale, and anecdotal notes tracked study activities and challenges. Results Twenty-three participants completed baseline, and 16 (70.0%) completed the study. Daytime and nighttime wearable adherence averaged 60.1% and 47.7%, respectively. Wearable adherence was highest at the earlier phase of the study (67.7%) and plateaued after overtime. User-related and technical challenges included digital illiteracy, protocol nonadherence, low motivation, measurement errors, and short battery life. Unique challenges included wearable design concerns and sleep problems. Conclusions This study demonstrates the feasibility of wearable use and highlights the potential to overcome challenges. Proactively sharing insights can facilitate wearable technology adoption for both participants and researchers.

Research on innovative design of intelligent wearable products based on human machine engineering and bionics

Designing intelligent wearable products entails integrating human factors, engineering, and bionics to develop ergonomic, efficient and convenient products. Human-machine engineering is a discipline that addresses the integration between the user wearing a particular system and improving the relationship between the user and the system. At the same time, bionics is an approach that aims to mimic biological systems and structures to enhance the performance of a particular product. This research explores the possibility of integrating these specializations to design new and enhanced wearable technology products with improved usability, convenience, and flexibility for practical usage. A detailed analysis of human biomechanics and ergonomic requirements established design parameters to ensure that wearable devices could be seamlessly integrated into daily life without hindering user movement. Bionic principles, such as the flexibility of animal joints and the energy-efficient movements of natural organisms, were applied to optimize the mechanical and structural aspects of the devices. This approach enabled the creation of products that mimic the natural dynamics of the human body, offering improved responsiveness and functionality. Prototypes were developed based on human-centred design principles and evaluated using simulation and testing environments. Wearables such as exoskeletons, bright clothing, and health-monitoring devices were examined for their ability to adapt to various physical conditions and environmental changes. Results demonstrate a significant increase in user comfort, reduction in mechanical strain, and enhanced performance, validating the effectiveness of integrating human-machine engineering and bionics in wearable design.

MEMS and ECM Sensor Technologies for Cardiorespiratory Sound Monitoring-A Comprehensive Review.

This paper presents a comprehensive review of cardiorespiratory auscultation sensing devices (i.e., stethoscopes), which is useful for understanding the theoretical aspects and practical design notes. In this paper, we first introduce the acoustic properties of the heart and lungs, as well as a brief history of stethoscope evolution. Then, we discuss the basic concept of electret condenser microphones (ECMs) and a stethoscope based on them. Then, we discuss the microelectromechanical systems (MEMSs) technology, particularly focusing on piezoelectric transducer sensors. This paper comprehensively reviews sensing technologies for cardiorespiratory auscultation, emphasizing MEMS-based wearable designs in the past decade. To our knowledge, this is the first paper to summarize ECM and MEMS applications for heart and lung sound analysis.

A wearable exhaled breath condensate (EBC) collector with controllable condensation microfluidics and a branched hydrophilic film

In previous research, exhaled breath condensate (EBC) analysis has emerged as a promising noninvasive method for assessing human health, potentially increasing patient testing acceptance. However, current EBC collection devices require cooling equipment for temperature reduction, leading to issues such as increased size, increased energy consumption, and a lack of real-time collection capability. In this study, an EBC collector was developed that integrates controllable condensation microfluidics with a biomimetic water-collecting film. Microfluids induce an endothermic reaction by rapidly dissolving water and NH4NO3 within the chamber, reducing the surface temperature to 3.5 °C. When positioned inside a mask, exhaled air undergoes condensation and collection on the branched biomimetic film. Human tests were conducted to analyze caffeine and nicotine in the collected EBC samples using LC–MS, demonstrating the device’s advantages in terms of power-free operation, wearable design, and rapid sample collection for metabolite detection.

Battery-free optoelectronic patch for photodynamic and light therapies in treating bacteria-infected wounds

Light therapy is an effective approach for the treatment of a variety of challenging dermatological conditions. In contrast to existing methods involving high doses and large areas of illumination, alternative strategies based on wearable designs that utilize a low light dose over an extended period provide a precise and convenient treatment. In this study, we present a battery-free, skin-integrated optoelectronic patch that incorporates a coil-powered circuit, an array of microscale violet and red light emitting diodes (LEDs), and polymer microneedles (MNs) loaded with 5-aminolevulinic acid (5-ALA). These polymer MNs, based on the biodegradable composite materials of polyvinyl alcohol (PVA) and hyaluronic acid (HA), serve as light waveguides for optical access and a medium for drug release into deeper skin layers. Unlike conventional clinical photomedical appliances with a rigid and fixed light source, this flexible design allows for a conformable light source that can be applied directly to the skin. In animal models with bacterial-infected wounds, the experimental group with the combination treatment of metronomic photodynamic and light therapies reduced 2.48 log10 CFU mL−1 in bactericidal level compared to the control group, indicating an effective anti-infective response. Furthermore, post-treatment analysis revealed the activation of proregenerative genes in monocyte and macrophage cell populations, suggesting enhanced tissue regeneration, neovascularization, and dermal recovery. Overall, this optoelectronic patch design broadens the scope for targeting deep skin lesions, and provides an alternative with the functionality of standard clinical light therapy methods.

Design and validation of dual-point time-differentiated photoplethysmogram (2PPG) wearable for cuffless blood pressure estimation

Background & objectivesMeasurement of blood pressure (BP) in ambulatory patients is crucial for at high-risk cardiovascular patients. A non-obtrusive, non-occluding device that continuously measures BP via photoplethysmography will enable long-term ambulatory assessment of BP. The aim of this study is to validate the metasense 2PPG cuffless wearable design for continuous BP estimation without ECG. MethodsA customized high-speed electronic optical sensor architecture with laterally spaced reflectance pulse oximetry was designed into a simple unobtrusive low-power wearable in the form of a watch. 78 volunteers with a mean age of 32.72 ± 7.4 years (21 to 64), 51% male, 49% female were recruited with ECG-2PPG signals acquired. The fiducial features of the 2PPG morphologies were then attributed to the estimator. A 9–1 K-fold cross-validation was applied in the ML. ResultsThe correlation for PTT-SBP was 0.971 and for PTT-DBP was 0.954. The mean absolute error was 3.167±1.636 mmHg for SBP and 6.4 ± 3.9 mm Hg for DBP. The ambulatory estimate for SBP and DBP for an individual over 3 days with 8-hour recordings was 0.70–0.81 for SBP and 0.42–0.51 for DBP with a ± 2.65 mmHg for SBP and ±2.02 mmHg for DBP. For SBP, 98% of metasense measurements were within 15 mm Hg and for DBP, 91% of metasense measurements were within 10 mmHg ConclusionsThe metasense device provides continuous, non-invasive BP estimations that are comparable to ambulatory BP meters. The portability and unobtrusiveness of this device, as well as the ability to continuously measure BP could one day enable long-term ambulatory BP measurement for precision cardiovascular therapeutic regimens.

Analyzing the Thermal Characteristics of Three Lining Materials for Plantar Orthotics.

The choice of materials for covering plantar orthoses or wearable insoles is often based on their hardness, breathability, and moisture absorption capacity, although more due to professional preference than clear scientific criteria. An analysis of the thermal response to the use of these materials would provide information about their behavior; hence, the objective of this study was to assess the temperature of three lining materials with different characteristics. The temperature of three materials for covering plantar orthoses was analyzed in a sample of 36 subjects (15 men and 21 women, aged 24.6 ± 8.2 years, mass 67.1 ± 13.6 kg, and height 1.7 ± 0.09 m). Temperature was measured before and after 3 h of use in clinical activities, using a polyethylene foam copolymer (PE), ethylene vinyl acetate (EVA), and PE-EVA copolymer foam insole with the use of a FLIR E60BX thermal camera. In the PE copolymer (material 1), temperature increases between 1.07 and 1.85 °C were found after activity, with these differences being statistically significant in all regions of interest (p < 0.001), except for the first toe (0.36 °C, p = 0.170). In the EVA foam (material 2) and the expansive foam of the PE-EVA copolymer (material 3), the temperatures were also significantly higher in all analyzed areas (p < 0.001), ranging between 1.49 and 2.73 °C for EVA and 0.58 and 2.16 °C for PE-EVA. The PE copolymer experienced lower overall overheating, and the area of the fifth metatarsal head underwent the greatest temperature increase, regardless of the material analyzed. PE foam lining materials, with lower density or an open-cell structure, would be preferred for controlling temperature rise in the lining/footbed interface and providing better thermal comfort for users. The area of the first toe was found to be the least overheated, while the fifth metatarsal head increased the most in temperature. This should be considered in the design of new wearables to avoid excessive temperatures due to the lining materials.

Multiscale Textile‐Based Haptic Interactions

Wearable haptic devices transmit information via touch receptors in the skin, yet devices located on parts of the body with high densities of receptors, such as fingertips and hands, impede interactions. Other locations that are well‐suited for wearables, such as the wrists and arms, suffer from lower perceptual sensitivity. The emergence of textile‐based wearable devices introduces new techniques of fabrication that can be leveraged to address these constraints and enable new modes of haptic interactions. This article formalizes the concept of “multiscale” interaction, an untapped paradigm for haptic wearables, enabling enhanced delivery of information via textile‐based haptic modules. In this approach, users choose the depth and detail of their haptic experiences by varying their interaction mode. Flexible prototyping methods enable multiscale haptic bands that provide both body‐scale interactions (on the forearm) and hand‐scale interactions (on the fingers and palm). A series of experiments assess participants’ ability to identify pressure states and spatial locations delivered by these bands across these interaction scales. A final experiment demonstrates the encoding of three‐bit information into prototypical multiscale interactions, showcasing the paradigm's efficacy. This research lays the groundwork for versatile haptic communication and wearable design, offering users the ability to select interaction modes for receiving information.

Intelligent perceptual textiles based on ionic-conductive and strong silk fibers

Endowing textiles with perceptual function, similar to human skin, is crucial for the development of next-generation smart wearables. To date, the creation of perceptual textiles capable of sensing potential dangers and accurately pinpointing finger touch remains elusive. In this study, we present the design and fabrication of intelligent perceptual textiles capable of electrically responding to external dangers and precisely detecting human touch, based on conductive silk fibroin-based ionic hydrogel (SIH) fibers. These fibers possess excellent fracture strength (55 MPa), extensibility (530%), stable and good conductivity (0.45 S·m–1) due to oriented structures and ionic incorporation. We fabricated SIH fiber-based protective textiles that can respond to fire, water, and sharp objects, protecting robots from potential injuries. Additionally, we designed perceptual textiles that can specifically pinpoint finger touch, serving as convenient human-machine interfaces. Our work sheds new light on the design of next-generation smart wearables and the reshaping of human-machine interfaces.

Automated ABR and MMN extraction using a customized headband for hearing screening

ObjectiveStimuli-elicited EEG responses, known as Event-Related Potentials (ERPs), reflect the health status of underlying electrophysiological processes and are frequently used for scanning sensory pathways. Current ERP extraction systems are expensive, complex, and bulky. This study aims to overcome these limitations by developing and validating a bimodal auditory ERP extractor headband. MethodsAn affordable, portable bimodal auditory ERP extractor was developed and validated for ABR (Auditory Brainstem Response) and MMN (Mismatch Negativity) response interpretation. Auditory stimuli were created using Presentation software. Adaptive filtering-based extraction was performed in EEGLAB (MATLAB) to derive the neural inferences. Extracted responses from n = 5 young adults were validated against CE-certified acquisition systems used in clinical practice. ResultsValidation results showed the grand average responses of ABR and MMN for n = 5 subjects matched. Furthermore, with and without stimuli ERP analysis showed significant differences for identified features (p = 0.00794 for ABR wave-V amplitudes, p = 1.22 * 10−5, and p = 2.62 * 10−5 for MMN peak latencies and area under the curves), ensuring that the response was due to the presented auditory stimuli. ConclusionThe results confirm the competency of the developed system to obtain MMN and ABR from young adults. A clear contrast between latency-amplitude scatter plots further ensures the competency of a developed system to acquire ABR and MMN. SignificanceThe novelty of the study is an easy-to-operate, affordable ERP extractor with adaptive filtering, wearable design, and configurable stimuli. This system can be a potential solution for large-scale hearing screening, providing detailed neural insights, including averaged responses and inter-trial variabilities.

Co-Designing Sensory Feedback for Wearables to Support Physical Activity through Body Sensations

Many technologies for promoting physical activity (PA) give limited importance to critical variables for engagement in PA, such as negative body perceptions. Here, we aim to address this gap by incorporating barriers and experienced body sensations into the design process for wearables and body-based devices thus expanding the design space for such technologies. We first report four co-design workshops with physically inactive participants (n=9); in these workshops, we explored tangible tools (i) to sensitize people to body sensations experienced when facing barriers to PA and (ii) to ideate how haptic and auditory feedback could transform body sensations to increase body-awareness and engagement in PA; results show several interactive sensorial patterns with potential to inform the design of body transformation wearables. These were validated through a follow-up workshop (n=13 participants) and reflections based on insights from a literature review. Our findings are significant for the design of ubiquitous technology to support and initiate PA in everyday contexts through a novel approach of transforming body perceptions/ sensations related to PA barriers. We contribute design inspirations and cards for identifying barriers to PA and to empower designers and researchers to integrate them early in the design process.

Mathematical Modeling and Statistical Analysis of Elederly Fall Detection System Using Improved Support Vector Machine

This research focuses on enhancing the safety of elderly individuals through early fall detection using mathematical modelling and statistical analysis of machine learning techniques for the application and effectiveness of elderly fall detection. Falls among the elderly can lead to severe consequences, necessitating timely intervention. Leveraging machine learning algorithms, this innovative open-source project analyses sensor data from wearable sensors like accelerometers, gyroscopes, and magnetometers, along with environmental data such as temperature and humidity, to promptly identify fall patterns. The project uses a dataset containing 14 variables, including age, sex, medical indicators, and more, collected from diverse subjects and activities. The results obtained during the testing phase underscore the importance of refining the model through dataset adjustments. As the physical, cognitive, and sensory functions decline with age, the risk of falls increases, highlighting the need for fall detection and prevention systems. This research reviews the latest machine learning-based systems for fall detection and prevention, analyzing them based on various parameters. It identifies support vector machines and wearable devices as common tools, but emphasizes the need for broader studies in different contexts. The paper also visualizes the performance metrics of ML algorithms in conjunction with various wearables and outlines future research directions, including energy efficiency, sensor fusion, context awareness, and wearable design, to advance fall detection and prevention for the elderly.

Full-fiber triboelectric nanogenerators with knitted origami structures for high impact resistance intelligent protection fabric.

Next-generation fabrics with excellent protection and intelligent sensing abilities will be beneficial to protect the elderly from accidents, as the ageing population will be a global challenge in the next decade. However, for widely used techniques such as fabric coating and multi-layer compositing, maintaining a balance between comfortability, stable anti-impact protection, and multi-function such as intelligent monitoring remains elusive. Herein, a full-fiber composite yarn with triboelectric ability was developed, which was then woven into an origami-structured knitted fabric (OSKF). Due to the coaxial torsional structure, the composite yarn exhibited outstanding fracture strength (219.18 MPa). The full-fiber multi-scale structure design endowed the OSKF with significantly improved energy absorption capacity (absorbing > 85% of the applied force) and the desired self-powered sensing performance without affecting the comfortability. The OSKF also had a unique ability to respond to various hazardous situations, such as external mechanical force stimuli, cutting by a sharp object, and accidental falls. This work sheds light on a new path toward the design of next-generation smart protection wearables based on knitted fabric structure design-based full-fiber materials.

Wearable Loop Sensors for Knee Flexion Monitoring: Dynamic Measurements on Human Subjects.

Goals: We have recently introduced a new class of wearable loop sensors for joint flexion monitoring that overcomes limitations in the state-of-the-art. Our previous studies reported a proof-of-concept on a cylindrical phantom limb, under static scenarios and with a rigid sensor. In this work, we evaluate our sensors, for the first time, on human subjects, under dynamic scenarios, using a flexible textile-based prototype tethered to a network analyzer. An untethered version is also presented and validated on phantoms, aiming towards a fully wearable design. Methods: Three dynamic activities (walking, brisk walking, and full flexion/extension, all performed in place) are used to validate the tethered sensor on ten (10) adults. The untethered sensor is validated upon a cylindrical phantom that is bent manually at random speed. A calibration mechanism is developed to derive the sensor-measured angles. These angles are then compared to gold-standard angles simultaneously captured by a light detection and ranging (LiDAR) depth camera using root mean square error (RMSE) and Pearson's correlation coefficient as metrics. Results: We find excellent correlation (≥ 0.981) to gold-standard angles. The sensor achieves an RMSE of 4.463° ± 1.266° for walking, 5.541° ± 2.082° for brisk walking, 3.657° ± 1.815° for full flexion/extension activities, and 0.670° ± 0.366° for the phantom bending test. Conclusion: The tethered sensor achieves similar to slightly higher RMSE as compared to other wearable flexion sensors on human subjects, while the untethered version achieves excellent RMSE on the phantom model. Concurrently, our sensors are reliable over time and injury-safe, and do not obstruct natural movement. Our results set the ground for future improvements in angular resolution and for realizing fully wearable designs, while maintaining the abovementioned advantages over the state-of-the-art.

COMPUTATIONAL WEARABLES DESIGN: SHOE SOLE MODELING AND PROTOTYPING

Computational wearables design is based on the integration of algorithms into the design process. The use of computational design tools offers a series of advantages in the wearable product design modelling because a complete family of products can be produced with a limited effort from the designer, while at the same time geometries with high complexity can be dealt with a manageable way. The present paper aims to create the appropriate code for modelling shoe soles. The use of a visual programming language leads to a better understanding of the produced code and aims in controlling and optimising the output models. Following the proposed methodology, 3D scanning technologies and plantar pressure diagrams are used for introducing the sole customised geometry, and then the proposed algorithm creates a variety of alternatives of the final shoe sole geometry. As a result, both the customisation and the high number of alternative designs lead to increased creativity and customer satisfaction. Due to the complexity of the geometry produced, 3D printing technologies are incorporated for the prototype implementation.

Moving Matter: A methodology for material-led collaborations

Interdisciplinary movement artists and educators Rob Kitsos and Meagan Woods share the process behind Moving Matter: material-led collaborative choreographies, a research-creation project that offers a methodology for rethinking the dynamism between raw materials, garments, and the body. Moving Matter steers the locus of choreography and wearable design away from human hierarchy to instead support truer collaboration amongst all moving materials, both human and non-human. In a challenge to normative structures where costumery operates ‘in service’ of dance, the textile designs for Moving Matter do not support the complete autonomy and freedom of moving humans; the wearables have striking characteristics of their own that limit what the human body can do. In establishing parameters, we intend not to reverse the hegemony of human-led design to human-suppressed design, but to re-recognize the agency of all matter through material-led collaborations that support distributed power and collective, innovative approaches to making. This paper details the artists’ studio process and their methodology template for material-led collaborative process that can be adapted for practices within and beyond performance and art disciplines.

User-Centered Perspectives on the Design of Batteryless Wearables

Batteryless wearables use energy harvested from the environment, eliminating the burden of charging or replacing batteries. This makes them convenient and environmentally friendly. However, these benefits come at a price. Batteryless wearables operate intermittently (based on energy availability), which adds complexity to their design and introduces usability limitations not present in their battery-powered counterparts. In this paper, we conduct a scenario-based study with 400 wearable users to explore how users perceive the inherent trade-offs of batteryless wearable devices. Our results reveal users’ concerns, expectations, and preferences when transitioning from battery-powered to batteryless wearable use. We discuss how the findings of this study can inform the design of usable batteryless wearables.