Regarding the implantable strain sensor, we completed the design, manufacturing, and characterization of a strain sensor using non-bioresorbable materials. The sensor was engineered with multiple layers of varying modulus values to optimize performance within the in-body environment. By conducting simulation studies, the optimal placement of electrodes and the ideal thickness and modulus of each layer were determined. The fabrication process employed silicone-based polymers and precise laser micromachining to integrate electrodes seamlessly into the polymer layers. This work established a robust design that will facilitate the subsequent development of bioresorbable sensors.
Then, we focused on the development of an electrochemical sensor for monitoring biomarkers for cardiac events. The project team developed a model to determine the necessary electrode area for effective detection. Utilizing high-resolution 3D printing and molding techniques, a bioresorbable micro-needle structure was fabricated. Laser micromachining was then used to create precise masks for metal evaporation, enhancing the sensor's functionality. The successful rapid detection of troponin using this bioresorbable microneedle structure marks a significant milestone, demonstrating the sensor's capability for real-time cardiac monitoring.
For communication, advancements were made in the design and implementation of a battery-free ultrasonic wireless data transmission system. We introduced a frequency-based passive ultrasonic communication method, enabling electronics-free data transfer from deep tissue capacitive sensor implants. A prototype device featuring an ultrasonic antenna made from a single piezoceramic crystal and a capacitive sensor was developed and successfully demonstrated in vitro. This system effectively detected resonance frequency shifts corresponding to sensor responses, showcasing its potential for reliable, real-time data transmission.
For encapsulation, we developed an encapsulation layer with triggered bioresorption to regulate the implant's lifespan. We synthesized and conducted comprehensive material characterizations to assess the reliability and predictability of the degradation profile of the developed polymer. A notable achievement was the demonstration of light triggered degradation of the bioresorbable polymer, providing a controlled mechanism for implant dissolution without requiring additional surgical procedures. Ongoing studies continue to explore the polymer's degradation limits, ensuring its performance meets practical application standards.
By the conclusion of the first half of the 2ND-CHANCE project, we have successfully developed and tested critical components essential for bioresorbable, wireless cardiac monitoring implants. The project has advanced sensor technologies, developed innovative wireless communication systems, and established a reliable bioresorption mechanism. These accomplishments lay a solid foundation for integrating all components into a functional implantable device, poised for further testing and future applications.
