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Abstract The demand for glucose monitoring devices has witnessed continuous growth from the rising diabetic population. The traditional approach of blood glucose (BG) sensor strip testing generates only intermittent glucose readings. Interstitial fluid‐based devices measure glucose dynamically, but their sensing approaches remain either minimally invasive or prone to skin irritation. Here, a sweat glucose monitoring system is presented, which completely operates under rest with no sweat stimulation and can generate real‐time BG dynamics. Osmotically driven hydrogels, capillary action with paper microfluidics, and self‐powered enzymatic biochemical sensor are used for simultaneous sweat extraction, transport, and glucose monitoring, respectively. The osmotic forces facilitate greater flux inflow and minimize sweat rate fluctuations compared to natural perspiration‐based sampling. The epidermal platform is tested on fingertip and forearm under varying physiological conditions. Personalized calibration models are developed and validated to obtain real‐time BG information from sweat. The estimated BG concentration showed a good correlation with measured BG concentration, with all values lying in the A+B region of consensus error grid (MARD = 10.56% (fingertip) and 13.17% (forearm)). Overall, the successful execution of such osmotically driven continuous BG monitoring system from passive sweat can be a useful addition to the next‐generation continuous sweat glucose monitors.

Abstract Swallowing is an ensemble of voluntary and autonomic processes key to maintaining our body’s homeostatic balance. Abnormal swallowing (dysphagia) can cause dehydration, malnutrition, aspiration pneumonia, weight loss, anxiety, or even mortality—especially in older adults—by airway obstruction. To prevent or mitigate these outcomes, it is imperative to regularly assess swallowing ability in those who are at risk of developing dysphagia and those already diagnosed with it. However, current diagnostic tools such as endoscopy, manometry, and videofluoroscopy require access to clinical experts to interpret the results. These results are often sampled from a limited examination timeframe of swallowing activity in a controlled environment. Additionally, there is some risk of periprocedural complications associated with these methods. In contrast, the field of epidermal sensors is finding non-invasive and minimally obtrusive ways to examine swallowing function and dysfunction. In this review, we summarize the current state of wearable devices that are aimed at monitoring swallowing function and detecting its abnormalities. We pay particular attention to the materials and design parameters that enable their operation. We examine a compilation of both proof-of-concept studies (which focus mainly on the engineering of the device) and studies whose aims are biomedical (which may involve larger cohorts of subjects, including patients). Furthermore, we briefly discuss the methods of signal acquisition and device assessment in relevant wearable sensors. Finally, we examine the need to increase adherence and engagement of patients with such devices and discuss enhancements to the design of such epidermal sensors that may encourage greater enthusiasm for at-home and long-term monitoring.

Embedded-chip planar silver-elastomer interconnect technology is developed with flexible substrates and demonstrated for on-skin biophotonic sensor applications. This approach has several benefits and is also consistent with chip-thinning where the chip thickness is 100 microns and less. The key benefits from this approach arise because both the bottom and top sides are now available as flat surfaces for 3D integration of other components. It also results in the lowest electrical parasitics compared to flipchip with adhesives or printed-ramp interconnections with surface-assembled devices. Embedding of chips in flexible carriers was accomplished with direct screen-printed interconnects onto the chip pads in substrate cavities. Silver nanoflake-loaded polyurethane is utilized in the embedded-chip packages to provide the desired lower interconnect resistance and also reliability in flexible packages under deformed configurations. Viscoelastic models were utilized to model the interconnection stresses. Planar interconnects in flexible substrates are developed with conductive silver-loaded elastomer interconnects. This approach is compared to direct chip-on-flex assembly technology for reliability under bending and high-temperature storage. The embedded-chip technology is demonstrated through biophotonic sensor applications where light sources (LEDs) and photodetectors are embedded inside the package. Functional validation in bent configuration at low curvatures is shown by measuring pulse rate and muscle activity with human subjects. By extending this technology to nanowires in elastomers, further enhancement in electrical and reliability performance can be achieved.