Ga@MXene-based flexible wearable biosensor for glucose monitoring in sweat

Abstract

Most wearable biosensors struggle to balance flexibility and conductivity in their sensing interfaces. In this study, we propose a wearable sensor featuring a highly stretchable, three-dimensional conductive network structure based on liquid metal. The sensor interface utilizes a patterned Ga@MXene hydrogel system, where gallium (Ga) grafted onto MXene provides enhanced electrical conductivity and malleability. MXene provides excellent conductivity and a three-dimensional layered structure. Additionally, the chitosan (CS) hydrogel, with its superior water absorption and stretchability, allows the electrode to retain sweat and closely stick to the skin. The sensor demonstrates a low limit of detection (0.77 μM), high sensitivity (1.122 μA⋅μM⁻¹⋅cm⁻²), and a broad detection range (10-1,000 μM), meeting the requirements for a wide range of applications. Notably, the sensor can also induce perspiration in the wearer. The three-dimensional porous structure of the Ga@MXene/CS biosensor ensures excellent conductivity and flexibility, making it suitable for a variety of applications.

Keywords: Applied sciences; Health sciences; Natural sciences.

Graphical abstract

Figure 1

Preparation diagram and detection schematic of wearable sensors (A) Preparation diagram of Ga@MXene/CS. (B) Detection principle schematic diagram of Ga@MXene/CS sensor.

Figure 2

Morphology and elemental distribution images of Ga@MXene/CS (A–C) SEM images of Ga@MXene/CS. Scale bar: 50, 10, and 1 μm in order. (D–I) EDS images of Ga@MXene/CS. Scale bar: 1 μm.

Figure 3

Characterization of structure and composition of materials (A and B) XRD patterns for Ga/CS, MXene/CS, and Ga@MXene/CS. (C) XPS survey spectra of Ga/CS, MXene/CS, and Ga@MXene/CS. (D–F) Ga 3d spectrum, Ti 2p spectrum, and O 1s spectrum of Ga/CS, MXene/CS, and Ga@MXene/CS.

Figure 4

Electrochemical characterization of the wearable sensor (A–C) CV curves of (A) Ga@MXene/CS, (B) MXene/CS, and (C) Ga/CS at different scan rates. (D) The calibration of peak currents vs. the root-squared scan rate. (E) EIS of the Ga/CS, MXene/CS, and Ga@MXene/CS. (F) Equivalent circuit and charge transfer resistance of the Ga/CS, MXene/CS, and Ga@MXene/CS. Data represented as mean ± standard error of the mean.

Figure 5

Glucose detection performance and the detection principle diagram (A) DPV curves of Ga@MXene/CS sensor. (B) Calibration curve of Ga@MXene/CS biosensor current versus concentration. Data represented as mean ± standard error of the mean. (C) Ga@MXene/CS sensor detection schematic.

Figure 6

Performance tests of the wearable sensors (A) Actual image of Ga@MXene/CS sensor. (B–D) Test chart of the heating function of the Ga@MXene/CS sensor. (E) DPV curves of Ga@MXene/CS sensors for real sample detection. (F) Recovery plot of Ga@MXene/CS sensor for real sample detection. Data represented as mean ± standard error of the mean.