Opportunity
The increasing focus on non-invasive health monitoring has driven the development of wearable biosensors that analyze sweat, a biofluid rich in biomarkers like electrolytes, metabolites, and pH, which reflect nutritional and metabolic status. However, existing wearable sweat sensors face a significant limitation: they rely on natural physical activity, such as jogging, to induce sufficient sweating for analysis. This dependency makes them ineffective for sedentary individuals, including the elderly, those with physical disabilities, or people who are less active, as they cannot naturally produce the sweat required for reliable, on-demand monitoring. Furthermore, methods that use external power supplies (e.g., batteries) to electrically stimulate sweat extraction often impose a burden on the design of thin, soft, skin-interfaced electronics due to the required current levels. There is a clear need for a self-sufficient, user-friendly system that can effectively extract and analyze sweat without relying on strenuous exercise or cumbersome external power sources, particularly to enable continuous healthcare monitoring for sedentary populations.
Technology
This patent discloses a Sweat Extraction and Monitoring System (SEMS) that integrates several innovative technologies to create a fully self-powered platform for on-demand sweat analysis. The core innovation is the use of a triboelectric nanogenerator (TENG) to convert light mechanical energy from simple actions like tapping or pressing into electrical energy. This TENG powers iontophoresis electrodes in contact with the skin. The iontophoresis process, often enhanced with a sweat-inducing agent like carbachol, uses this TENG-generated current to non-invasively stimulate localized sweat secretion without the need for exercise. The extracted sweat is channeled into a microfluidic network designed with multiple inlets for rapid collection. A key feature is the integration of a sweat-activated battery (SAB), which uses the collected sweat as an electrolyte to power the system's electronics. Once activated by the sweat, the SAB provides stable power to biosensors and a microcontroller. The biosensors, which can include ion-selective electrodes for sodium (Na+) and potassium (K+) and a polyaniline-based pH sensor, analyze the sweat in real-time. The sensed data is processed by a microcontroller and transmitted wirelessly (e.g., via NFC) to an external computer system or smartphone for display and further analysis. This closed-loop system—where TENG-induced sweat activates the SAB which then powers the sensing and data transmission—eliminates the need for any external battery, making it a compact, wearable, and entirely self-powered solution.
Advantages
- Enables effective sweat extraction and monitoring for sedentary individuals who cannot rely on physical exercise to produce sweat.
- Provides a fully self-powered system by combining a TENG for energy harvesting and a sweat-activated battery (SAB) for stable power supply, eliminating the need for external batteries.
- Offers a non-invasive and needle-free method for sweat stimulation through iontophoresis.
- Features a flexible, skin-interfaced design with a flexible printed circuit board (FPCB) and encapsulation materials like PDMS for comfortable and secure wearability.
- Accelerates sweat collection and analysis time (e.g., ~8.7 minutes with stimulation vs. ~35.9 minutes at rest) for rapid health status feedback.
- Incorporates a microfluidic channel design optimized for efficient sweat collection from low-volume samples.
- Demonstrates high sensitivity, selectivity, and linear response in detecting key sweat biomarkers (Na+, K+, pH).
- The SAB exhibits excellent flexibility and maintains stable electrical output under mechanical deformation (bending, twisting).
Applications
- Continuous Health Monitoring for Sedentary and Elderly Populations: Enables regular, non-invasive tracking of hydration status and electrolyte balance without requiring physical exertion.
- Personalized Sports Medicine and Athletic Training: Monitors athletes' sweat rate and electrolyte composition in real-time to optimize hydration strategies and prevent heat-related illnesses.
- Fitness and Wellness Tracking: Allows gym-goers and fitness enthusiasts to monitor workout intensity and hydration levels for more effective training regimens.
- Clinical Diagnostics: Potentially aids in the diagnosis and management of conditions that affect sweat gland function or composition, such as cystic fibrosis or diabetes.
- Remote Patient Monitoring: Facilitates the wireless transmission of health data to healthcare providers for telemedicine and chronic disease management.
- Personalized Nutrition and Metabolic Health: Provides insights into an individual's metabolic state through the analysis of sweat metabolites and ions.
