Stretchable electronic devices using novel material and structural approaches

J. Wang, P.S. Lee
Nanyang Technological University,
Singapore

Keywords: soft electronic, stretchable devices, electronic skin

Summary:

Stretchable electronics are a new type of mechanical deformable devices which are gaining increasing interests and believed to be one of the essential technologies for the next generation electronic applications. The excellent mechanical conformability in these devices enables them to maintain functionality under rigorous conditions with mechanical deformations such as flexing, twisting, stretching, and folding etc, leading to unprecedented applications that cannot be addressed with the conventional technologies. Our research group has successfully developed novel methods for constructing stretchable electronic devices, including: Photodetector: We demonstrated stretchable photodetectors fabricated with nanowire networks that were assembled by facile spray-coating or vacuum filtration methods. The nanowire devices embedded in elastic polymer matrix can be flexed, twisted or stretched up to 100% strain with well-maintained functionalities, as shown in Figure 1. Strain sensor & Temperature sensor: We have fabricated high-strain sensors based on crumpled graphene embedded in elastomer matrix. The strain sensor can be used to detect strains up to 100% for real time human motion monitoring. Utilizing the semiconducting behavior of the crumpled graphene which changes its resistivity under different temperatures, we also demonstrated a stretchable thermistor with similar device structures. The thermistor can be strained to 50% with maintained functionality, which will be an ideal candidate for temperature sensing and mapping in conformable and wearable detection systems. Electroluminescent devices: Our novel stretchable transparent electrodes (silver nanowires embedded in elastomer) have been used for light-emitting devices which can maintain 87% of the emission intensity under 100% strain as shown in Figure 2a. Actuation under electric field can be attained with dynamic shape changes of the light-emitting device. A super-elastic light-emitting device could be stretched up to 700% strain when ionic conductors were employed, as shown in Figure 2b.