Not surprisingly, advances in areas like radar technologies and photonics were very much in evidence at the SPIE Defense and Commercial Sensing conference in Baltimore last week. But the wide-ranging technical conference also uncovered some interesting developments in materials, enabling the development of flexible, high-strength electronics for industrial, medical, and other applications.
Several speakers discussed various approaches in a session titled “Nano-engineered Stretchable Electrodes: Fundamentals, Fabrication, and Applications.” Jang-Ung Park of Yonsei University in Korea discussed the development of ultra-long, metal nanofibers to develop more stretchable nanofibers. Park envisions such materials being used in applications such as smart contact lenses to replace plastic, as well as in protein sensors and heaters. Park also believes the nanofibers can be fabricated into stretchable electrodes with 3D printed features for interconnects.
Cungjiang Yu, a professor at the University of Houston, talked about the formation of rubber texture-like, stretchable electronics that would replace inflexible, brittle substrates like ceramics. Yu hopes to develop various rubbery electronics circuits―transistors, logic devices, even device arrays―and would like to extend the concept of robotic “skin” to sense temperature, and even rubbery sensors that could translate sign language.
Flexible substrates were also discussed by Eui-Hyeok Yang of the Stevens Institute of Technology. Yang and his team have been researching the development of flexible electrodes that can conformally wrap around curvilinear shapes. Yang says that with roll-to-roll manufacturing, stretchable electrodes could lead to advances in flexible photovoltaics, sensor arrays, self-powered wearable optoelectronics, and more.
Another interesting take on materials was discussed in a session titled “Biodegradable Bioelectronics and Biosensors.” Ramendra Pal, a professor at Virginia Commonwealth University, discussed the harnessing of two key silk proteins― fibroin and silcon― to help pattern circuits on flexible substrates. Pal believes harnessing these components could pave the way for a new generation of biodegradeable, flexible electronics circuits and substrates.
Pal has led several research efforts at Virginia Commonwealth to demonstrate the viability of the silk proteins for various electronics substrates. Pal says conductive soluble “silk ink” has been used to form photolithographic patterns, using the proteins.
The silk particles can be embedded into flexible substrates that can be bent in various shapes, without significantly sacrificing electrical performance. Pal adds micro supercapacitors with high energy storage have been developed using the silk proteins.
Pal notes that the electrical performance of circuits using the silk particles may not be as high as that of common circuit traces such as silver or copper. However, he adds that silk-based particles can suffice for applications where electrical performance is not critical but biocompatibility is.