A Wearable Surface-Enhanced Raman Scattering Sensor for Label-Free Molecular Detection

Abstract

A wearable surface-enhanced Raman scattering (SERS) sensor has been developed as a patch type to utilize as a molecular sweat sensor. Here, the SERS patch sensor is designed to comprise a sweat-absorbing layer, which is an interface to the human skin, an SERS active layer, and a dermal protecting layer that prevents damage and contaminations. A silk fibroin protein film (SFF) is a basement layer that absorbs aqueous solutions and filtrates molecules larger than the nanopores created in the β-sheet matrix of the SFF. On the SFF layer, a plasmonic silver nanowire (AgNW) layer is formed to enhance the Raman signal of the molecules that penetrated through the SERS patch in a label-free method. A transparent dermal protecting layer (DP) allows laser penetration to the AgNW layer enabling Raman measurement through the SERS patch without its detachment from the surface. The molecular detection capability and time-dependent absorption properties of the SERS patch are investigated, and then, the feasibility of its use as a wearable drug detection sweat sensor is demonstrated using 2-fluoro-methamphetamine (2-FMA) on the human cadaver skin. It is believed that the developed SERS patch can be utilized as various flexible and wearable biosensors for healthcare monitoring.

Human metabolite detection by surface-enhanced Raman spectroscopy

“…Wearable devices based on SERS-active nanomaterials have also been reported, since integrating optically active plasmonic materials on flexible substrates allows the direct and sensitive recognition of metabolites [ [135] , [136] , [137] ]. SERS-active wearable devices, such as T-shirts made of flexible SERS fibers, can be designed as sensitive sweat sensors, which can monitor health by measuring sweat electrolytes.…”

A Wearable PVA Film Supported TiO2 Nanoparticles Decorated NaNbO3 Nanoflakes‐Based SERS Sensor for Simultaneous Detection of Metabolites and Biomolecules in Human Sweat Samples

“…In the past few decades, wearable health care devices have gathered significant attention owing to their noninvasive, reliable, and sensitive monitoring of vital metabolites in biofluids like sweat, saliva, tears which provide the diagnostic parameters of diseases and other physiological conditions. [1,2] Generally, skin interfaced wearable devices are well known for their multiparameter detection capabilities that provide critical information charge transfer resonance mechanism between the targeted biomolecule and the substrate. [14,15] Generally, the noble metal-based SERS substrates are widely reported for the detection of metabolites and biomolecules in biofluids like blood serum, sweat, etc.…”

“…In the past few decades, wearable health care devices have gathered significant attention owing to their noninvasive, reliable, and sensitive monitoring of vital metabolites in biofluids like sweat, saliva, tears which provide the diagnostic parameters of diseases and other physiological conditions. [ 1,2 ] Generally, skin interfaced wearable devices are well known for their multiparameter detection capabilities that provide critical information through biochemical, biophysical, and kinematic signals of the human body. [ 3 ] Among these, the biochemical signals are observed from the sweat‐based biomarkers such as biomolecules (e.g., ascorbic acid (AA), uric acid (UA)), electrolytes (e.g., sodium, potassium), metabolites (e.g., glucose, urea, lactate), and hormones which provide the vital information about the human physiological condition.…”

“…The electromagnetic mechanism was reported with the noble metal substrates (such as gold (Au), silver (Ag)) which exhibits surface plasmon resonance and amplifies the signals by 10 10 to 10 11 folds by the presence of nanogaps known as hotspots and the electromagnetic field. [1] The chemical mechanism relies on the photoinduced Sweat is one of the non-invasive diagnostic biofluids that provides critical information about human health. In this work, a wearable sweat sensor integrated with a polymer-based fluid absorption layer modified with titanium oxide (TiO 2 ) nanoparticles decorated sodium niobate (NaNbO 3 ) nanoflakes in porous polyvinyl alcohol (PVA) film matrix is demonstrated for the detection of vital metabolites (such as glucose and urea) and biomole cules (ascorbic acid (AA) and uric acid (UA)) in human sweat samples via surfaceenhanced Raman scattering (SERS).…”

In Situ Electrodeposition of Gold Nanostructures in 3D Ultra‐Thin Hydrogel Skins for Direct Molecular Detection in Complex Mixtures with High Sensitivity

“…[1][2][3][4][5][6] The practical ability of SERS to amplify Raman signals via localized surface plasmon coupling on nanostructured metals has rendered the technique attractive for the detection of various chemicals [7][8][9][10][11] and biomolecules. [12][13][14] Despite the remarkable sensitivity of SERS, the selective detection of small molecules in the presence of interferents, such as proteins, lipids, and colloids, remains an important challenge. [15][16][17][18] In complex matrices (e.g., biological fluids or foods), metal surfaces are prone to fouling via the nonspecific adsorption of macromolecules, which inhibits the access of target molecules to SERS-active nanogaps among metallic nanostructures.…”