A non-enzymatic flexible and wearable sensor based on thermal transfer printing technology for continuous glucose detection in sweat

Non-invasive, flexible wearable sensors are an important method to continuously measure glucose in sweat for diabetes and human health monitoring and management. However, how to create an alkaline environment at any time so that CuO based sensors can be applied to wearable devices to detect sweat glucose while finding a way to efficiently and quickly produce the sensors in small batches have been a challenge. Herein, we report a non-enzymatic thermal transferred flexible and wearable sensor based on CuO/CaTiO₃ for continuous glucose detection in sweat. The sensor is manufactured using thermal transfer printing technology, which offers advantages like low cost, ease of operation, and rapid small batch production. CuO is known for its excellent electrocatalytic activity, making it a suitable candidate for glucose oxidation. Meanwhile, CaTiO₃ particles provide a large specific surface area, good biocompatibility, and electrical conductivity, which enhance the electron transfer rate during detection and broaden the linear range of glucose detection. Specially designed NaOH/Nafion/PEO blend film make the measurements always in a strong alkali environment without any pretreatment and preparation. The synthesized material with this as-prepared flexible and wearable sensor exhibits superior performance towards glucose monitoring, such as high sensitivity of 487.3 μA mM⁻¹ cm⁻² with limit of detection(LOD) 0.75 μM, wide dynamic linear range from 0.01 mM to 2 mM and fast response time of less than 0.1 s. Additionally, the proposed sensor also exhibited excellent biocompatibility, selectivity, reproducibility and flexibility, as well as good stability with about 88 % of its initial activity after 5 weeks’ storage and it has been successfully applied for the detection of glucose concentration in human sweat real samples. This research contributes to the development of flexible and wearable sensors for non-invasive sweat diagnostics, enabling continuous glucose monitoring for various applications in healthcare and wellness.