Piezoresistive sensors based on biodegradable poly(glycerol sebacate) elastomer

This study employed a microwave-assisted synthesis technique to fabricate biodegradable poly(glycerol sebacate) (PGS) elastomer, which was subsequently used as a substrate for creating highly stretchable piezoresistive sensors. The sensors were fabricated by spray coating techniques to deposit conductive materials, namely carbon nanofibres, onto the PGS substrate. In this experiment, three curing temperatures (125 ℃, 130 ℃, and 135 ℃) were employed, each with four curing durations of 20 h, 24 h, 36 h, and 40 h. Analysis of the obtained PGS samples through tests on swelling degree and water absorption revealed that the PGS sample cured at the lowest temperature and for the shortest duration (125 ℃/20 h) exhibited the highest sol content, swelling ratio, and water absorption, measuring 52%, 220%, and 16%, respectively. In contrast, data for the PGS sample cured at 135 ℃/40 h were 23%, 130%, and 8.5%. This indicates that PGS samples cured at lower temperatures and shorter durations have higher sol content, indicating lower crosslinking density. Regarding mechanical properties, the sample cured at 125℃/20 h showed the maximum elongation at break and the minimum Young's modulus among all samples, measuring 180% and 0.06 MPa, respectively. As the curing temperature and duration increased, the elongation at break decreased, and the modulus increased. For the sample cured at 135 ℃ for 40 h, these values were 37% and 0.94 MPa, respectively. This observation demonstrated the flexibility to tailor the mechanical properties of PGS films by adjusting the curing parameters. Furthermore, the effects of the area density of conductive nanomaterials on sensor performance were thoroughly investigated. Finally, the degradation performance of PGS substrates in a PBS solution was studied, Samples with low crosslinking density (125℃/20 h) experienced a mass loss exceeding 30% over 30 days. These findings contribute to the development of biodegradable sensors with customizable properties, holding promise for various biomedical and environmental sensing applications.