Self-Adhesive, Biocompatible, Wearable Microfluidics with Erasable Liquid Metal Plasmonic Hotspots for Glucose Detection in Sweat

Abstract

Sweat is a noninvasive metabolite that can provide clinically meaningful information about physical conditions without harming the body. Glucose, a vital component in sweat, is closely related to blood glucose levels, and changes in its concentration can reflect the health status of diabetics. We introduce a self-adhesive, wearable microfluidic chip with erasable liquid metal plasmonic hotspots for the precise detection of glucose concentration in sweat. The self-adhesive, wearable microfluidic chip is made from modified polydimethylsiloxane (PDMS) with enhanced stickiness, enabling conformal contact with the skin, and can collect, deliver, and store sweat. The plasmonic hotspots are located inside the microfluidic channel, are generated by synthesizing silver nanostructures on liquid metal, and can be removed in the alkaline solution. It indicates the erasable and reproducible nature of the plasmonic hotspots. The detection method is based on surface-enhanced Raman spectroscopy (SERS), which allows for accurate detection of the glucose concentration. To enhance the sensitive detection of glucose, the SERS substrate is modified by 4-mercaptophenylboronic acid to achieve the limit of detection of 1 ng/L glucose, which is much lower than the physiological conditions (7.2–25.2 μg/L). The developed microfluidic chip is soft, stretchable, and nontoxic, bringing new possibilities to wearable sweat-sensing devices.

Organ-on-Chip immunostaining method for three-dimensional identification and study of immune cells responding to drug-treated tumor cells

“…These microfluidic devices are made by using a specific biomaterial such as Poly-dimethylsiloxane (PDMS). It is a biocompatible silicone-derived elastomer, exhibiting excellent optical qualities and allowing direct observation by microscopy (Michielin & Maerkl, 2022; Wei et al, 2023; Yuan et al, 2023). Briefly, the microfabrication process can be resumed into i) fabrication of microstructured epoxy resin mold, ii) prototyping of PDMS channel microstructures by standard soft lithography, iii) bonding of PDMS chips to microscope slides or multiwell plates by oxygen plasma treatment and iv) chip functionalization poly-L-Lysine, if needed (see Note 5 ).…”

Recent Development and Applications of Stretchable SERS Substrates

“…A novel erasable and reproducible plasmonic hot-spot developed by synthesizing silver nanostructures on liquid metal was reported recently, and the hot-spots can be removed in alkaline solution. The self-adhesive, biocompatible, and stretchable device is able to detect glucose concentrations as low as 1 ng/L [119]. Stretchable SERS substrates can also integrate with other technologies such as paperbased microfluidics to achieve desired functions.…”