Materials and Device Designs for an Epidermal UV Colorimetric Dosimeter with Near Field Communication Capabilities

Abstract

Ultraviolet (UV) solar radiation is a leading cause of skin disease. Quantitative, continuous knowledge of exposure levels can enhance awareness and lead to improved health outcomes. Devices that offer this type of measurement capability in formats that can seamlessly integrate with the skin are therefore of interest. This paper introduces materials, device designs, and data acquisition methods for a skin‐like, or “epidermal,” system that combines colorimetric and electronic function for precise dosimetry in the UV‐A and UV‐B regions of the spectrum, and for determination of instantaneous UV exposure levels and skin temperature. The colorimetric chemistry uses (4‐phenoxyphenyl)diphenylsulfonium triflate (PPDPS‐TF) with crystal violet lactone (CVL) and Congo red for UV‐A and UV‐B operation, respectively, when integrated with suitable optical filters. Coatings of poly(ethylene‐vinylacetate) (PEVA) protect the functional materials from sunscreen and other contamination. Quantitative information follows from automated L*a*b* color space analysis of digital images of the devices to provide accurate measurements when calibrated against standard nonwearable sensors. Techniques of screen printing and lamination allow aesthetic designs and integration with epidermal near field communication platforms, respectively. The result is a set of attractive technologies for managing UV exposure at a personal level and on targeted regions of the body.

Battery-free, wireless sensors for full-body pressure and temperature mapping

“…Applications range from those in hospital care and clinical medicine to physical rehabilitation, fitness/wellness tracking, awareness and cognitive state assessment, and human-machine interfaces (7, 8). Although use of an individual device on a targeted region of the body enables clinically validated measurement modalities in electrophysiology, temperature, pressure, blood oximetry, and others, using multiple separate devices across different anatomical locations simultaneously could expand the possibilities to enable measurements across the body for tracking of position-dependent body processes, disease states, and/or external stimuli (8, 9). …”

High Performance, Biocompatible Dielectric Thin‐Film Optical Filters Integrated with Flexible Substrates and Microscale Optoelectronic Devices

“…These flexible filters obtained in this study not only illustrate their utilities to modulate device performance when integrating with microscale LEDs and PV detectors, but also exhibit ideal biocompatibilities both in vitro and in vivo. As an essential optical component, such filters can be readily implemented into wearable and implantable optoelectronic systems for biomedical uses, including fluorescence sensing, optogenetic interrogation, and health monitoring . Besides LEDs and photodetectors, such filters can also be combined with other photonic devices such as microscale lasers and waveguides for versatile applications like beam steering and spectral shaping .…”

“…Advanced optoelectronic devices play an important role in biomedical fields like bioimaging, epidermal sensing, phototherapy, and laser surgery . More recently, researchers have been investing considerable efforts in the exploitation of implantable optoelectronic devices and systems, which have capabilities to deliver and receive optical power and signals directly within the deep tissue.…”

Electro‐Photoluminescence Color Change for Deformable Visual Encryption

“…A number of organisms use high energy UV radiations for adaptive camouflage with concealment, [ 1–3 ] protection, [ 4–6 ] or signaling, [ 7–9 ] through the mechanisms of photonic crystal, [ 10 ] surface morphological control, [ 5,11 ] chemical fluorophore, [ 7,9,12 ] and radiation reflection. [ 8,13,14 ] There have been many attempts to mimic such radiation‐responsive color changes and several studies demonstrated responsive display, [ 15–17 ] encryption, [ 18,19 ] colorimetric sensors, [ 20,21 ] and data recording. [ 22,23 ] Unfortunately, such color changing systems are useful only in the presence of bright external light.…”