A highly flexible Ni–Co MOF nanosheet coated Au/PDMS film based wearable electrochemical sensor for continuous human sweat glucose monitoring

Abstract

The development of flexible substrate materials and nanomaterials with high electrochemical performance is of great significance for constructing efficient wearable electrochemical sensors for real-time health monitoring. Herein, a wearable electrochemical sweat sensor based on a Ni–Co MOF nanosheet coated Au/polydimethylsiloxane (PDMS) film was prepared for continuous monitoring of the glucose level in sweat with high sensitivity. First, a stretchable Au/PDMS film based three-electrode system was prepared by chemical deposition of a gold layer on the hydrophilic treated PDMS. Then, Ni–Co MOF nanosheets with high electrocatalytic activity were synthesized by a facile solvothermal method and modified on the Au/PDMS electrode. The electrocatalytic activity of the Ni–Co MOF nanosheets synthesized under different Ni : Co ratios was investigated. The Ni–Co MOF/Au/PDMS (NCAP) film electrode showed excellent electrochemical performance for glucose detection with a wide linear range of 20 μM to 790 μM and a high sensitivity of 205.1 μA mM⁻¹ cm⁻². In addition, the flexible sensor shows high stability and a good electrochemical response to glucose when stretched and bent to different levels. Moreover, it maintained long-term stability and high selectivity for glucose monitoring. Lastly, a sweat-absorbent cloth was used to cover the working area of the sensor and was fixed with a needle and thread to form a wearable sweat glucose sensor. The sensor can be attached to the skin for stable, accurate and continuous monitoring of glucose levels in human sweat for one day. This work validates the potential of our high-performance wearable sensor for out-of-clinic health monitoring.