A Review on Flexible Substrate Materials for Stretchable Electronic Devices

Abstract

Stretchable electronic devices have exerted an overt impact on developments in wearable electronics, biomedical devices, soft robotics and the Internet of Things (IoT), with flexible substrate materials playing a fundamental role as building blocks. This extensive study provides a detailed comparison and contrast of the properties (mechanical, electrical, environmental) of polymer-based, organic compounds, bio-based materials as well as hybrids as substrates for stretchable electronics. Polymer substrates like polydimethylsiloxone (PDMS) and polyurethane have made it possible to obtain stretchability (150%-200%) along with biocompatibility, crucial for making wearable sensors or implants with sensitivity down to 0.5 kPa⁻¹ Biodegradability within 30 days makes organic substrates such as cellulose and silk part of the sustainable materials that derived functional properties, suitable for disposable biosensors. The graphene /silver nanowires hybrid substrates exhibit relatively low sheet resistance (10 Ω/sq) and high transmittance (89%), which is well suited for stretchable circuits and displays. Scalability is further supported by spin-coating, 3D printing, and roll-to-roll processing techniques but uniformity as well as cost remains into question. Key limitations include mechanical fatigue (typically 10,000 cycles), conductivity decrease under flexion, high processing costs ($50–100/kg for organic substrates) and regulatory challenges in the biomedical field. The review focuses on novel trends such as self-healing polymers which recover up to 90% of mechanical properties and bio-inspired substrates for enhanced biocompatibility. Future work, which targets at low-cost and easy scale-up of nanomaterial synthesis, 4D printing for dynamic structures, and integrating with AI/IoT to realize intelligent devices (50 µW/cm²), is also discussed. This work revisits the studies of substrates, as well as actives and passives in other works to present an all-embracing view regarding the substrate materials, applications, and challenges that subsequently helps in paving the way for sustainable scalability of stretchable electronics.