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Device Technologies and Biomedical Robotics

Device Technologies and Biomedical Robotics - Poster Session E

Poster W5 - Real-Time and Unobtrusive Health Monitoring for Personalized Healthcare

Saturday, October 26, 2024
10:00 AM - 11:00 AM EST
Location: Exhibit Hall E, F & G

Introduction:  The shift towards personalized and remote healthcare has accelerated the development of wearable devices that can continuously monitor physical vital signs as well as biochemical markers. However, major challenges exist in developing a multifunctional wearable system that can perform autonomous sweat induction and sampling, real-time sweat rate monitoring, and continuous multiplexed biomarker analysis. To address these challenges, we have developed a highly powerful battery-free lab on the skin with multifunctional capabilities that performs autonomous sweat extraction, microfluidic sweat sampling, and multimodal sweat analysis using a broad spectrum of electrochemical techniques across activities from rest to exercise, powered solely via a flexible quasi-2D perovskite solar cell module that provides ample power under a broad range of outdoor and indoor illumination conditions.

Materials and

Methods:  The process for making a flexible perovskite solar cell involves cleaning and cutting an ITO-covered PET substrate using various solutions, spin-coating a PDMS solution onto a glass substrate, and placing the flexible substrate on top. Cr-Au bus bars are then deposited using thermal evaporation, followed by spin-coating a PEDOT:PSS solution and annealing. The perovskite solution is prepared and deposited using an anti-solvent procedure and then annealed, followed by spin-coating a PCBM solution and a TiOx solgel. Finally, Cr/Au contacts are evaporated, and the device is encapsulated.
The wearable device consists of power management, data processing, wireless communication, electrochemical instrumentation, and iontophoretic induction blocks. The power management block utilizes an energy harvesting PMIC and voltage regulator to charge the energy storage capacitor efficiently. A PSoC BLE module is used for data processing and wireless communication, while an electrochemical front-end and voltage buffers are used for electrochemical instrumentation. The iontophoresis induction block produces a constant current with high compliance voltage. The device underwent testing with electrochemical measurements and was compared to an electrochemical workstation.
The daily disposable microfluidic sweat sensor patch consists of an inkjet-printed electrochemical sensor array on a polyimide substrate and a laser-patterned microfluidic system on PET/medical tape. Silver ink is used for interconnects, reference electrode, and interdigitated impedance electrodes. Carbon electrodes are printed for iontophoresis, counter, and working electrodes, which are further electrochemically modified as glucose, sodium, and pH sensors. The system is applied to the skin to monitor biomarkers throughout the day under various conditions.

Results, Conclusions, and Discussions: The wearable device consists of a reusable flexible perovskite solar cell module and a flexible printed circuit board, along with a disposable daily patch containing iontophoresis electrodes, a microfluidic module, and a multiplexed electrochemical sweat biosensor array. All biosensing electrodes and interconnects were fabricated using inkjet printing for low-cost mass production. The device can analyze a broad spectrum of sweat biomarkers using various techniques and can wirelessly transmit information to a custom mobile app. The device is energy-efficient and can extract and analyze sweat across various activities and illumination conditions for prolonged periods.
FPSCs were developed to operate with high efficiency even under low indoor lighting. The FPSCs have a p-i-n architecture that includes a quasi-2D perovskite photoactive layer with a large organic spacer, alpha-methylbenzylamine (MBA), that facilitates the formation of a quasi-2D perovskite structure with large grain size and improved defect passivation. The device has achieved record-breaking power conversion efficiency (PCE) of up to 41.4% when tested with a monochromatic light source, while still remaining efficient under low indoor lighting conditions. The module's mechanical stability was also confirmed to withstand 2000 bending cycles.
For on-body validation, the wearable device uses light energy harvesting to power iontophoresis and multiplexed sweat biosensing sequences, allowing efficient and prolonged sweat extraction for dynamic biomarker analysis. In sedentary and exercise studies, the device accurately monitored sweat glucose, pH, Na+, sweat rate, and skin temperature levels in real-time, demonstrating high potential for non-invasive glucose monitoring. The device was also tested in real-life scenarios, showing its ability to perform prolonged cross-activity multimodal monitoring of sweat biomarkers. While the battery-free version requires access to light, integrating a small battery could enable 24-hour operation.

Acknowledgements (Optional):