Wearable, epidermal devices for assessment of swallowing function

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.