Highly Scalable, Wearable Surface‐Enhanced Raman Spectroscopy

Abstract

The last two decades have witnessed a dramatic growth of wearable sensor technology, mainly represented by flexible, stretchable, on‐skin electronic sensors that provide rich information of the wearer's health conditions and surroundings. A recent breakthrough in the field is the development of wearable chemical sensors based on surface‐enhanced Raman spectroscopy (SERS) that can detect molecular fingerprints universally, sensitively, and noninvasively. However, while their sensing properties are excellent, these sensors are not scalable for widespread use beyond small‐scale human health monitoring due to their cumbersome fabrication process and limited multifunctional sensing capabilities. Here, a highly scalable, wearable SERS sensor is demonstrated based on an easy‐to‐fabricate, low‐cost, ultrathin, flexible, stretchable, adhesive, and biointegratable gold nanomesh. It can be fabricated in any shape and worn on virtually any surface for label‐free, large‐scale, in situ sensing of diverse analytes from low to high concentrations (10–106 × 10−9 m). To show the practical utility of the wearable SERS sensor, the sensor is tested for the detection of sweat biomarkers, drugs of abuse, and microplastics. This wearable SERS sensor represents a significant step toward the generalizability and practicality of wearable sensing technology.

Place & Play SERS: sample collection and preparation-free surface-enhanced Raman spectroscopy

“…In this application, the Place & Play SERS measurement scheme is highly effective because it closely resembles the practical situation of controlled-drug detection in potential crime scenes such as when the target surface is frequently touched by a hand contaminated with the controlled drugs, compared with the previous SERS measurements in which the sample was dropped on the gold/PVA nanomesh substrate. 13 As shown in Fig. 7a, the prominent peaks that appeared at about 450 cm −1 , 650 cm −1 , 1050 cm −1 , and 1500 cm −1 agree with those previously reported.…”

“…The gold/ PVA nanomesh substrate shows a high SERS signal enhancement of ∼10 8 , high sensitivity down to ∼10 nM of rhodamine 6G (R6G), and high SERS measurement reproducibility (i.e., spectrum-to-spectrum consistency) due to a high density of plasmonic hot spots in three dimensions that originate from the nanometer-sized gaps of gold nanobres in the gold/PVA nanomesh as well as the edges of the gold nanobres. 13 Specically, we characterized the sensitivity of the gold/PVA nanomesh substrate in the Place & Play SERS measurement scheme and then used the scheme to conduct SERS measurements of both wet and dry objects under nearly real-world conditions. For SERS measurements of dry objects, we only needed to spray them with water before placing the SERS substrate on the surface of the objects.…”

Emerging biotransduction strategies on soft interfaces for biosensing

“…104 In addition to composite materials, the enhancement factor (EF) of a stretchable gold nanomesh was estimated to be 10 8 in a flexible and adhesive SERS sensor system. 105 An Ag nanocube array, as another widely used plasmonic nanomaterial, could generate strong electromagnetic enhancement from sharp edges with an EF of 1.4 × 10 10 . With the SERS-based sensor chip, COVID-19 was identified under 5 min by a hand-held breathalyzer with >95% sensitivity and specificity (Fig.…”

Surface-enhanced Raman scattering as a potential strategy for wearable flexible sensing and point-of-care testing non-invasive medical diagnosis

“…To achieve high SERS sensitivity and uniformity, Wang et al created a wearable SERS ultra-thin and flexible multi-functional sensor (SF-AAO-Au) based on a micro-nano array of cavity particle structure of silk fibroin, anodic aluminum oxide (AAO) and gold nanoparticles. The high SERS sensitivity and uniformity are due to the efficient enhancement ability of porous 3D PIC structure and highly ordered periodic array ( Liu, et al, 2022 ; Wang, et al, 2022 ). As illustrated in Figure 1E , Li et al (2022) designed a quasi-periodic PIC Raman substrate structure based on silver nanoparticles and anodic alumina templates to achieve sensitive detection at the single-molecule level and further improved the detection accuracy by introducing molybdenum disulfide as an internal standard.…”