The incidence of diabetes is increasing at an alarming rate, and regular glucose monitoring is critical in order to manage diabetes. Currently, glucose in the body is measured by an invasive method of blood sugar testing. Blood glucose (BG) monitoring devices measure the amount of sugar in a small sample of blood, usually drawn from pricking the fingertip, and placed on a disposable test strip. Therefore, there is a need for non-invasive continuous glucose monitoring, which is possible using a sweat sensor-based approach. As sweat sensors have garnered much interest in recent years, this study attempts to summarize recent developments in non-invasive continuous glucose monitoring using sweat sensors based on different approaches with an emphasis on the devices that can potentially be integrated into a wearable platform. Numerous research entities have been developing wearable sensors for continuous blood glucose monitoring, however, there are no commercially viable, non-invasive glucose monitors on the market at the moment. This review article provides the state-of-the-art in sweat glucose monitoring, particularly keeping in sight the prospect of its commercialization. The challenges relating to sweat collection, sweat sample degradation, person to person sweat amount variation, various detection methods, and their glucose detection sensitivity, and also the commercial viability are thoroughly covered.

In recent years, the importance of flexible and textile electronics in the field of wearable devices has continuously increased, as they are expected to replace conventional wires that exhibit limited resistance to the mechanical stress occurring in on-body applications. Wearable health devices (WHDs) can provide physiological information about various body parts and employ distributed sensor networks. Among the sensors typically integrated within WHDs, those based on the I²C communication protocol are very common and exploit signals transmitted at frequencies up to hundreds of kilohertz. Therefore, robust communication is required to guarantee a proper transmission of the signal at those frequencies. In this context, we have realized embroidered conductive threads exhibiting a lower resistance, appositely designed to replace conventional wires in a microcontroller-based wearable device employing I²C sensors. A commercial conductive thread (silver coated polyamide) was used to embroider the conductive lines on to cotton fabric. Preliminary measurements were performed to characterize the response of these materials to signals typically operated within the I²C communication protocol at different path lengths. Resistive measurements have also been performed to stimulate different environmental conditions, that is, temperature, the effect of sweating, and repeated washing cycles, also apply mechanical stress, i.e. twisting, with promising results that validate our conductive paths for digital signal communication.

Conductive threads are essential for enabling the functionality of e-textiles in sensor applications. However, in this field, there is still a need to study their practical usage, particularly thick embroidered structures. This study investigates the potential of using conductive embroidered structures as sensors and examines how different stitch types can affect the electrical properties of embroidered structures in e-textiles. The paper also explores the application of embroidered structures in twisting and temperature variation, and evaluates their stability when subjected to washing, abrasion and cyclic tension. Three rectangular structures with varying stitch types and geometries were embroidered and tested. The findings highlight the influence of stitch types on electrical properties and demonstrate how washing can affect the different stitch patterns. Furthermore, the structure with the largest jump length can be used in a design suitable for sensing twisting, while all three structures are suitable for detecting temperature variations. This research adds to the development of efficient and long-lasting embroidered electronics textile by providing significant insights for e-textile industrial production.

Accurate and consistent measurement of plantar pressure and gait analysis holds significant importance in guiding gait training for neurologically injured patients and others undergoing gait rehabilitation at home. In this paper, the fabrication of cost-effective force sensing resistors (FSRs) using rattan as a substrate and aluminum foil for sensing purposes is shown. A total of six unique combinations were generated by combining two types of rattan surfaces and three dissimilar materials (Kapton, blue cotton fabric, and white cotton fabric) for printing the carbon layer to create FSRs to print the carbon layer by an unconventional subtractive xurographic technique using a conductive layer of aluminum (foil). The sensitivity of all types of sensors was determined and compared using a compression test. All produced sensors showed the same characteristic diagram of the FSRs dependence resistance as commercial sensors. Two FSRs were selected to measure the pressure applied at the first metatarsal heads and the heel during the gait test. The test involved five subjects of different ages taking a hundred steps and wearing a custom insole created using the 3D printing fused deposition modeling (FDM) technique. The sensors successfully detected the force during the subjects’ walking and were not damaged even after the tests.

Minimizing Path Loss in Medical Wireless Sensors in Wireless Body Area Sensor Networks