Wearable, implantable sensors possible with flexible transistors

Using a smart transfer technique, a research team from Saudi Arabia has made flexible fin-shaped and metal-oxide-semiconductor field-effect transistors that could be placed on a variety of soft and asymmetric surfaces such as textile, wood, paper and plastic. 

Manufacturing wearable electronics by embedding such transistor-based sensors in clothes, paper- and plastic-based materials is possible, they say. 

Muhammad Mustafa Hussain, and his teammates from King Abdullah University of Science and Technology (KAUST), made the transistors on thin silicon wafers using an industry-standard process. To make them flexible, the scientists then peeled off the transistors from the silicon substrates, turned them upside down and placed them on a film coated with a dissolvable support layer.  

They then deposited a thin layer of elastomer polydimethylsiloxane (PDMS) and dissolved the support layer in acetone, releasing the thin-film device. 

When they transferred the device to paper, they found that it still retained its electrical properties and could even reduce any strain-related effects induced by bending. 

Textile and wood surfaces exhibited stronger adhesion to the device, compared with less porous plastic surfaces such as vinyl. Increasing the thickness of PDMS layer reduced strain-related effects in these devices, signaling their potential for making implantable, wearable and embedded sensors. 

“Currently, we are using these flexible transistors to make plant sensors that will be used in the realm of agriculture,” says Hussain.  

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