Researchers at Penn State say they have developed stretchy transistors using a new manufacturing method. While soft, elastic semiconductors and circuits could advance wearable medical devices and other emerging technologies, such high-performance electronics are difficult and expensive to manufacture.
Now, say the researchers, they are looking to make the process easier and cheaper with a new manufacturing method. Known as the lateral phase separation induced micromesh (LPSM) strategy, their process involves mixing a semiconductor and an elastomer — or rubber — and spin coating the liquid mixture precursors to fabricate rubbery semiconductor thin films.
The spin coated film automatically triggers a mechanism called lateral phase separation, which generates micromesh structures within seconds. The micromesh materials, which resemble a basket weave, are integral for allowing for mechanical stretch, say the researchers.
“The LPSM films used to create the stretchy semiconductors promise simultaneous efficient charge transport and mechanical stretchability,” says Cunjiang Yu, Dorothy Quiggle Career Development Associate Professor of Engineering Science and Mechanics and associate professor of biomedical engineering and of materials science and engineering.
The researchers used the LPSM method to create both p-type and n-type semiconductors, whose majority charge carriers are holes and electrons, respectively. Using both semiconductor types, the researchers created soft electronic devices such as transistors, inverters and photodetectors that can stretch to a large extent while maintaining functionality.
In addition, say the researchers, they created a rubbery bioelectronic device known as an epicardial patch and implanted it in a rodent.
“As the rat’s heart expanded and contracted with its heartbeat, the entirely rubber-based epicardial patch also moved with it,” says Yu. “We recorded multiple channels of electrophysiology readings simultaneously with the patch. Recording at multiple sites of the heart is important to identify cardiac problems such as arrhythmia.”
Going forward, the researchers say they hope to further optimize the LPSM process and to investigate the detailed properties of the semiconductor materials. They also plan to employ the LPSM semiconducting thin film in various high-performance integrated electronics and functional systems.