The New 3D Optical Graphene Detectors : Spider Webs Inspire

Human are always inspired by nature whether it is medical field of technological field. You can take NASA and other tech giants that take inspirations from nature. For example the aircraft designs are based on structure of owl to counter the gusty winds. In a research it was found that the wings of owl works as suspension system and helps to stabilize trajectory of the head and the torso in strong winds and also a team of researchers from the School of Mechanical Engineering and Automation, Beihang University, and the John A. Paulson School of Engineering and Applied Sciences, Harvard University, developed a tentacle-shaped robotic arm. And in this case the source of inspiration was an octopus and its tentacles. Chinese scientists are working on serpents in order to find how serpents can predict earthquakes. And there are many more examples in which nature is source of inspiration.

But now it was the turn of spiders and their webs. The architectures and shapes created by spiders are fascinating and complex and can form nets with high mechanical resistance. Researchers at Purdue University have decided to use these designs to perfect the technology of optical detectors. The shape is combined with the mechanical properties of graphene to achieve great mechanical adaptability and damage tolerance.

“We employed the unique fractal design of a spider web for the development of deformable and reliable electronics that can seamlessly interface with any 3D curvilinear surface” said Chi Hwan Lee, a Purdue assistant professor of biomedical engineering and mechanical engineering. “For example, we demonstrated a hemispherical, or dome-shaped, photo detector array that can detect both direction and intensity of incident light at the same time, like the vision system of arthropods such as insects and crustaceans”.

“The assembly technique presented in this work enables deploying 2D deformable electronics in 3D architectures, which may foreshadow new opportunities to better advance the field of 3D electronic and optoelectronic devices“, Lee said.

The research was also appreciated and supported by the National Science Foundation and the Air Force Research Laboratory, the results are published in the journal Advanced Materials. The facility provides unique capabilities for externally induced stress distribution on the sensor. The particular shape is also able to withstand small cuts while maintaining overall strength and function.

Researchers have taken inspiration both from the webs and compound eyes of spiders to create a 3D photo detection system with a large field of view and no aberration. To construct photodetector the team developed an organic-dye-sensitized Graphene hybrid composite. Graphene is famous for thin 2D version of carbon – offers superior optoelectronic properties and mechanical flexibility compared with alternatives like silicon. Graphene’s photosensitivity, however, is limited by its atomic thinness. The hybrid composite material developed by the researchers enhanced the material’s optical absorption, overcoming this limitation. The team began by micro-fabricating the photo detector array on a standard 2D silicon wafer. Using a wet transfer printing technique, the array was then assembled on a transparent hemispherical dome. The final design comprised 48-pixel photo detectors at the cross-junctions of the spiral and radial threads of the webbed array. The team writes that increasing the amount of spiral threads, radial threads or both while maintaining the device size would further improve the array’s spatial resolution.

In experiments, Lee says, the 3D photo detector demonstrated not only advanced optoelectronic functionality in detecting both direction and intensity of light, “but also superior photo-responsivity, compared to other similar counterparts, through the use of a graphene hybrid composite as a flexible and effective photoactive component.” The fractal design provided mechanical resilience as the researchers repeatedly attached and detached the device from planar and curved surfaces. Throughout these characterizations, the researchers write, the device’s photocurrent remained nearly unchanged at 653–666 μA. The team has filed a patent for its technology and is seeking partners moving forward.

Follow us @ Facebook : Advanced TechWorld