A Naked Eye‐Invisible Ratiometric Fluorescent Microneedle Tattoo for Real‐Time Monitoring of Inflammatory Skin Conditions

Abstract

The field of portable healthcare monitoring devices has an urgent need for the development of real‐time, noninvasive sensing and detection methods for various physiological analytes. Currently, transdermal sensing techniques are severely limited in scope (i.e., measurement of heart rate or sweat composition), or else tend to be invasive, often needing to be performed in a clinical setting. This study proposes a minimally invasive alternative strategy, consisting of using dissolving polymeric microneedles to deliver naked eye‐invisible functional fluorescent ratiometric microneedle tattoos directly to the skin for real‐time monitoring and quantification of physiological and pathological parameters. Reactive oxygen species are overexpressed in the skin in association with various pathological conditions. Here, one demonstrates for the first time the microneedle‐based delivery to the skin of active fluorescent sensors in the form of an invisible, ratiometric microneedle tattoo capable of sensing reactive oxygen species in a reconstructed human‐based skin disease model, as well as an in vivo model of UV‐induced dermal inflammation. One also elaborates a universal ratiometric quantification concept coupled with a custom‐built, multiwavelength portable fluorescence detection system. Fully realized, this approach presents an opportunity for the minimally invasive monitoring of a broad range of physiological parameters through the skin.

Microneedle patch tattoos

“…Although light and thermal stimuli serve as examples in this study, prior research has demonstrated novel chemistries and technologies for materials that respond to a broad range of different stimuli of interest in medicine and other applications, including glucose, enzymes, and pH ( Deirram et al., 2019 ; Kowalski et al., 2018 ; Linsley and Wu, 2017 ; Mu et al., 2018 ; Municoy et al., 2020 ; Ward and Georgiou, 2011 ; Wu et al., 2011 ). These functional materials and particles may be loaded into MN patches and delivered into the skin to monitor a variety of different physiological parameters ( Babity et al., 2022 ; He et al., 2021 ).…”

Portable Multi-Wavelength Fluorescence Measurement Device

“…Allowing intradermal administration for the quantitative monitoring of physiological and pathological parameters remotely without requiring trained personnel and complex instrumentation. For instance, its use was recently illustrated for the non-invasive monitoring of dermal inflammatory conditions [6]. Thus, it will be of great help for researchers and clinicians working with dermally injected fluorescent tracers.…”

“…The marker samples were purchased either from Lumiprobe or synthesized by the Faculty of Pharmacy at the Université de Montréal. Synthesis and characterization are described in [6]. Dilution series in Ethanol for the fluorescent markers Cy3, Cy5 and Cy7.5 were prepared to gather first data regarding the fluorescence intensity meter's performance.…”

“…To accomplish this, optical and electronic design choices require thorough consideration. Recent work showed that ratiometric fluorescent tattoos delivered using microneedles can be used to monitor physiological and pathological conditions [6], [7]. For the tattoo detection and monitoring potentials, a circular measurement area of 30 mm diameter of the skin has to be imaged.…”

Electrochemical Microneedles: Innovative Instruments in Health Care

“…An electrochemical sensor is an apparatus that converts the chemical quantity of a sample and into an electrical quantity based on the electrochemical property of the sample and to perform sensing detection [ 15 ]. Among these, miniaturized electrochemical sensors can be integrated in many types of wearable substrates; for example, electrochemical sensors integrated on microneedle patches can reach the dermal matrix fluid of human and animal skin for the systemic transdermal detection of various analytes [ 16 ]. In the wake of the development of microelectromechanical system (MEMS) technology [ 17 ], many miniaturized electrochemical sensors combined with microneedles have produced a variety of electrochemical microneedle sensors for monitoring biomarkers.…”