Wearables and smart skin as new tools for clinical practice and research in dermatology

Wearable technology, like smartwatches and wristbands, is not only growing in popularity among digitally-savvy consumers but also seeing more applications in healthcare.1 The foundation for the development of wearable technology, also known as wearables, grew out of a trend of increasing miniaturization and portability of electronics in the 1980s.2 More recently, this portability of wearables allows for the monitoring of diseases at home, which proved to be relevant during the coronavirus disease 2019 (COVID-19) pandemic.3, 4 Researchers from the Stanford University School of Medicine and the medical department of Case Western University demonstrated that it was possible to detect symptomatic cases of COVID-19 based on smartwatch data like heart rate, number of daily steps, and sleep duration. Changes in these data were used to correctly identify 81% of infected patients as potentially COVID-19 positive, illustrating the possible applications of wearables in better understanding the COVID-19 pandemic.4 Particularly in dermatology are wearables an emerging area of research fostered by technological developments (Table 1). In dermatology, wearables known as "smart skin" refer to sensors worn directly on the skin that measure a wide range of parameters in real-time analysis. Various physical quantities, like location, pressure, temperature, or humidity, can be integrated into measurements depending on the measuring method. Furthermore, research on smart skin is increasingly focusing on the detection of biomarkers in human fluids. For example, it is possible to detect medically relevant parameters like electrolytes, metabolites, proteins, and hormones in human sweat.5, 6 Researchers from the Department of Dermatology and Allergy at the Technical University of Munich are currently developing a miniaturized skin sensor in the form of a wristband to create personalized predictions of atopic eczema. Atopic eczema is a multifactorial skin disease that causes dry, itchy skin as well as psychological distress as a result of the physical symptoms in affected individuals.7, 8 Feared complications include eczema herpeticum and bacterial superinfections with Staphylococcus aureus, which can consequently lead to higher hospitalization rates.9-12 The goal of this skin sensor is to collect more information about potential triggers of atopic eczema as a complement to the otherwise mostly visual diagnoses of the disease. In addition to more conventional skin parameters, like the pH value or the transepidermal water loss, the skin sensor will measure electrodermal activity (EDA), which has previously not been studied in the context of atopic eczema.11 EDA can determine the resistance of the skin by measuring electrical potentials. This is related to the sympathetic tone of the skin and the activity of its sweat glands and thus correlates with stress level.13 Prior studies have examined the relevance of EDA as a diagnostic marker in other medical specialties, such as for perioperative stress in surgical specialties and severe depression in psychiatry.13, 14 Stress is an important trigger of atopic eczema exacerbation, but it often cannot be retroactively traced and identified.7 Researchers hope to quantify the relationship between stress and atopic eczema by recording fluctuations in EDA. Another method for measuring stress in the skin has been developed by two research groups from Stanford University and the Karolinska Institute. Together they built a sensor with a specific membrane that performs noninvasive measurements of cortisol in sweat glands. This membrane is permeable to ions in the absence of cortisol and in the presence of cortisol blocks the passage of ions, which are then detected by the sensor. The sensor's measurements showed high reliability and were not influenced by body temperature fluctuations. Furthermore, the sensor did not react to structural analogs of cortisol like cortisone, and various tests were conducted with artificial sweat and human sweat.5 In addition to smart skin, the skin's role in highly effective and targeted drug or vaccine delivery is currently being explored in medicine. For example, microneedling, which uses micron-sized needles to pass through the epidermis to reach dermal tissue, is a frequently used mechanism for vaccine delivery because of its painlessness, high bioavailability, and convenience. In addition, the high proportion of immune accessory cells and high rate of antigen presentation in the skin makes it an ideal target for immunization processes. Researchers from the University of Pittsburgh generated a microneedle array for the immunization against the Middle East respiratory syndrome coronavirus. Kim et al. targeted the spike protein (s-protein) and were able to elicit a stronger immune response than one would have received through a conventional injection with a traditional needle system. These promising results laid the foundation for the development of a similar system for SARS-CoV-2 in a mouse model. Preliminary results showed a strong antigen-specific antibody response at 2 weeks after immunization. This mechanism may offer a new approach to vaccinations amidst current discussions about the loss of immunity and need for booster vaccines during the COVID-19 pandemic.15 The potential of wearables in medicine is far from being exhausted. As previous research has demonstrated, applications of wearables like smart skin enable the collection of long-term data and continuous monitoring of patients in their everyday environments. Researchers can differentiate between those values collected during doctor's visits and those collected at home, allowing for a more accurate assessment of the patient. Wearable data may improve early disease detection, help develop new therapy options and limit disease progression. Limitations of wearables must be discussed, including age as a barrier to using among elderly patients and the dependency on working technology for accurate data collection.16, 17 Moreover, the integration of wearables into the daily life of patients offers significant room for improvement and development. The development of mobile health through digital assistants and mobile applications can create an interface between wearables, patients, and physicians.18 Wearables and mobile apps should, however, not be viewed as competition or replacements of physicians. Because it is not wearable or app instead of a doctor, but doctor and wearable together. By complementing data collected in more traditional contexts, wearables and smart skin may improve the accessibility and outcomes of healthcare for patients. And as this short outline illustrates, the speed and potential of this trend can only be expected to accelerate even further. This study received funding from the Department of Dermatology and Allergy, School of Medicine, Technical University of Munich. Open access funding enabled and organized by Projekt DEAL. The authors declare that there are no conflict of interests. Data sharing not applicable—no new data generated, or the article describes entirely theoretical research.

Abstract licence: CC BY-NC-ND

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   Microneedle array delivered recombinant coronavirus vaccines: Immunogenicity and rapid translational development · 2020

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