Stanford scientists have developed a new ultrathin, flexible electronic device that is biodegradable, an advance that may help tackle the problem of mounting electronic waste.
“We have been trying to mimic the function of human skin to think about how to develop future electronic devices,” said Zhenan Bao from Stanford University in the US. She notes how skin is stretchable, self-healable and also biodegradable — an attractive list of characteristics for electronics.
“We have achieved the first two (flexible and self- healing), so the biodegradability was something we wanted to tackle,” said Bao. The team created a flexible electronic device that can easily degrade just by adding a weak acid like vinegar. “This is the first example of a semiconductive polymer that can decompose,” said Ting Lei, a postdoctoral fellow at Stanford.
In addition to the polymer — essentially a flexible, conductive plastic — the team developed a degradable electronic circuit and a new biodegradable substrate material for mounting the electrical components.
This substrate supports the electrical components, flexing and moulding to rough and smooth surfaces alike. When the electronic device is no longer needed, the whole thing can biodegrade into nontoxic components. Bao had previously created a stretchable electrode modeled on human skin.
That material could bend and twist in a way that could allow it to interface with the skin or brain, but it could not degrade. That limited its application for implantable devices and contributed to waste. Bao said that creating a robust material that is both a good electrical conductor and biodegradable was a challenge, considering traditional polymer chemistry.
“We have been trying to think how we can achieve both great electronic property but also have the biodegradability,” Bao said. The team found that by tweaking the chemical structure of the flexible material it would break apart under mild stressors.
“We came up with an idea of making these molecules using a special type of chemical linkage that can retain the ability for the electron to smoothly transport along the molecule,” Bao said.
“But also this chemical bond is sensitive to weak acid - even weaker than pure vinegar,” he said. The result was a material that could carry an electronic signal but break down without requiring extreme measures. The study was published in the journal PNAS.
