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Thermal physiology and psychophysics are complex and nuanced, with significant variability between individuals. Wearable devices have the potential to offer customizable microclimate control. However, individual experiences with different supplemental heating strategies are likely to vary considerably in unconstrained environments. The physiological responses, psychophysical effects, and qualitative experiences of participants using five readily available heating strategies were collected in a quasi-field study environment ( n=17). Although all devices maintained or increased fingertip temperature, effects observed from controlled studies of thermal physiology are not clearly seen. Physiological, perceptual, and experiential data are presented, exploring heating technologies and thermal comfort in typical indoor environments. 

Textile-based compression devices are widely used in fields such as healthcare, astronautics, cosmetics, defense, and more. While traditional compression garments are only able to apply passive pressure on the body, there have been some efforts to integrate smart materials such as shape memory alloys (SMAs) to make compression garments active and controllable. However, despite the advances in this field, accurate control of applied pressure on the body due remains a challenge due to vast population-scale anthropometric variability and intra-subjects variability in tissue softness, even if the actuators themselves are fully characterized. In this study, we begin to address these challenges by developing a novel size-adjustable SMA-based smart tourniquet capable of producing a controllable pressure for circumferential applications. The developed prototype was tested on an inflatable pressure cuff wrapped around a rigid cylinder. The thermal activation of SMA coils was achieved through Joule heating, and a microcontroller and a programmable power supply are used to provide the input signal. To control the compression force, a closed-loop PID controller was implemented, and the performance of the system was evaluated in 5 different testing conditions for variable and cyclic compression levels. The experiments showed that the controlled system could follow the desired control pressure reference with a steady-state of 1 mmHg. The compression tourniquet is able to produce more than 33 mmHg with an average actuation rate of 0.19 mmHg/s. This is the first demonstration of accurate closed-loop control of an SMA-incorporated compression technology to the best of our knowledge. This paper enables new, dynamic systems with controllable activation and low-effort donning and doffing, with applications ranging from healthcare solutions to advanced spacesuit design.

 

The ability to control one's personal microclimate allows for customized comfort, reduced energy expenditure, and better human performance. Here we present the design of a multi-zone user-controllable heated jacket. The garment uses a multi-layer textile approach to provide e-textile heating and thermal insulation. Heating zones are controlled by the user through a sleeve-mounted multi-sensor e-textile interface. A custom textile-integrated 3D printed strain-relief support protects the interface and provides a counter-force for manual interaction. The garment is designed for everyday wearability in a physical and aesthetic form intended to blend in with everyday clothing. 

Many medical conditions, including sensory processing disorder (SPD), employ compression therapy as a form of treatment. SPD patients often wear weighted or elastic vests to produce compression on the body, which have been shown to have a calming effect on the wearer. Recent advances in compression garment technology incorporate active materials to produce dynamic, low bulk compression garments that can be remotely controlled. In this study, an active compression vest using shape memory alloy (SMA) spring actuators was developed to produce up to 52.5 mmHg compression on a child's torso for SPD applications. The vest prototype incorporated 16 SMA spring actuators (1.25 mm diameter, spring index = 3) that constrict when heated, producing large forces and displacements that can be controlled via an applied current. When power was applied (up to 43.8 W), the prototype vest generated increasing magnitudes of pressure (up to 37.6 mmHg, spatially averaged across the front of the torso) on a representative child-sized form. The average pressure generated was measured up to 71.6% of the modeled pressure, and spatial pressure nonuniformities were observed that can be traced to specific garment architectural features. Although there is no consistent standard in magnitude or distribution of applied force in compression therapy garments, it is clear from comparative benchmarks that the compression produced by this garment exceeds the demands of the target application. This study demonstrates the viability of SMA-based compression garments as an enabling technology for enhancing SPD (and other compression-based) treatment. 

This study explores efficient methods for production of customizable heated textiles. An electrical heating system using the Liberator40® conductive fiber, stitched in a serpentine pattern on stretch knit fabrics, was employed. Parameters including thread layers, pattern sizes, and different fiber-based substrates and covering were compared when analyzing resistance and temperature output. Results indicated that covered knit fabrics stitched with a 0.4cm serpentine spacing produced the most efficient measure of temperature.