Platform for Organ-on-Chip mechanobiological analysis and Stretchable biodegradable electrodes as strain sensor

In the last decades the huge development in the synthesis of reliable and effective biodegradable and biocompatible materials and the improvement of microfabrication techniques, have brought a wide increase in neural technologies. These devices can interface and interact with the neural system, especially for medical applications, increasing the healing process for different injuries and diseases. Among such applications, one of the most intriguing is based on scaffolds that help the regrowth and regeneration of peripheral nerves. In this project, the milestones for the complete design and fabrication of a biodegradable scaffold for the regeneration of peripheral nerves are deposited. Three main characteristics are mandatory for this scaffold: the use of biodegradable material, the presence of integrated stretchable electrodes, and the mechanical stimuli of the nerves to enhance their healing. However, due to the embryonal stage of the project, starting from scratches, the basic steps are needed to be fixed and set. The project is divided into two sub-parts, that were run in parallel. First, to be able to correctly stimulate nerves and enhance their regrowth, biological studies on neural cells were conducted. Nevertheless, to perform this research, a stage for mechanobiological studies needed to be designed and fabricated. This part was concerning the development of a platform that allows the controlled application of a radial strain to cell culture. All the different steps were performed, from the physics behind the device to its design, assembly, characterization, and biological validation. The system should be easily reproducible for use in many different laboratories and be highly compatible with a wide variety of imaging systems and biological specimens. The second sub-part of the project was concerning the development of biodegradable and stretchable electrodes for the recording of the signal and studying the strain in the system. The first target of this section was relying on the synthesis of different biodegradable and stretchable polymers, like POMaC, PGS, and PGSA. Then an electrode pattern has been designed in order to have a stretchable electrode, working also as a capacitive strain sensor, finding the most suitable microfabrication technique to deposit them on top of the biodegradable elastomer. Thus, an iron layer deposited by spark ablation was chosen. Finally, to test these devices a setup able to stretch the sample and measure the impedance was built.