Opportunity
The accurate and continuous monitoring of glucose levels is crucial for managing health conditions like diabetes. Traditional methods often require invasive blood sampling, which is painful, inconvenient, and carries risks of infection. While sweat offers a non-invasive alternative for glucose monitoring, existing sweat-based sensors predominantly rely on glucose oxidase enzymes. These enzyme-based sensors are inherently limited by the enzyme's sensitivity to environmental conditions such as temperature and pH, leading to instability, reduced lifespan, and compromised detection accuracy. This creates a significant barrier to developing reliable, long-term, and user-friendly wearable health monitors. There is a pressing need for a robust, stable, and highly sensitive glucose sensing technology that can operate effectively in the variable conditions of the human body without the drawbacks associated with biological enzymes.
Technology
This patent discloses an innovative enzyme-free glucose biosensor designed for non-invasive monitoring. The core innovation lies in its unique layered structure and the specific composition of its working electrode. The sensor comprises a flexible substrate layer, a sensor layer, and a top perfluorosulfonic acid-based polymer layer. The sensor layer features a three-electrode system (working, counter, and reference electrodes) built on a metal substrate. Crucially, the working electrode is modified with a composite material consisting of copper oxide (CuO) nanoparticles, calcium titanate (CaTiO₃) nanoparticles, and a perfluorosulfonic acid-based polymer in a specific weight ratio. This combination enables enzyme-free glucose detection through an electrocatalytic mechanism. The CuO nanoparticles undergo electrochemical oxidation to form Cu(III) species, which catalytically oxidize glucose to gluconolactone, subsequently hydrolyzing to gluconic acid, while the Cu(III) is reduced back. The CaTiO₃ nanoparticles dispersed on the CuO surface enhance the electron transfer rate and broaden the linear detection range. The perfluorosulfonic acid polymer increases conductivity and, together with the top polymer layer, acts as a selective cation-exchange membrane. This membrane significantly improves the sensor's anti-interference capability by repelling common sweat anions like lactate, urate, and chloride, thereby reducing signal noise. The sensor is fabricated using a cost-effective and flexible heat-transfer printing technique, allowing for customizable, precise, and environmentally friendly production on flexible materials like polyimide, making it ideal for wearable applications.
Advantages
- Enzyme-Free Operation: Eliminates instability and sensitivity limitations caused by enzyme deactivation due to environmental factors (temperature, pH).
- High Sensitivity and Wide Linear Range: The synergistic effect of CuO and CaTiO₃ nanoparticles provides high sensitivity (e.g., 487.3 μA mM⁻¹ cm⁻²) and a broad linear detection range (0.01 mM to 2 mM).
- Excellent Anti-Interference: The perfluorosulfonic acid-based layers selectively filter out common interfering substances in sweat (e.g., lactate, uric acid, NaCl, ascorbic acid).
- Good Stability: Demonstrates reliable performance over time, retaining 88% of initial current response after five weeks of storage.
- Biocompatibility and Flexibility: Safe for skin contact and built on a flexible substrate (e.g., polyimide), allowing it to conform comfortably to the body for continuous wear.
- Cost-Effective and Scalable Fabrication: Utilizes heat-transfer printing, a low-cost, design-flexible, and environmentally friendly manufacturing method suitable for mass production.
Applications
- Continuous, non-invasive glucose monitoring for diabetes management and pre-diabetes screening.
- Integration into smart wearable electronic devices such as fitness bands, smartwatches, and skin-adhesive patches for real-time health tracking.
- Personalized healthcare and wellness monitoring systems for athletes and general consumers.
- Point-of-care testing devices for rapid glucose analysis in sweat.
- Research tools for studying glucose dynamics and metabolism through non-invasive means.
