Pure graphene image sensor is a first, say scientists

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Scientists at Nanyang Technological University (NTU) in Singapore have fabricated an image sensor from graphene. The sensor is said to be highly sensitive and able to detect broad spectrum light, from the visible to mid-infrared.

The sensor was made by fabricating a graphene sheet into novel nano-structures. These ‘trap’ light-generated electron particles for a long time, resulting in a strong electric signal and a high photoresponse.

Assistant Professor Wang Qijie from NTU’s School of Electrical and Electronic Engineering and leader of the project, said it is believed to be the first time that a broad-spectrum, high photosensitive sensor has been developed using pure graphene. The work was published in Nature Communications.

The researchers claim the graphene sensor is 1,000 times more sensitive to light than current low-cost imaging sensors found in today’s compact cameras. It also uses 10 times less energy as it operates at lower voltages. When mass produced, graphene sensors are estimated to cost at least five times less to manufacture, say the scientists.

Graphene is a material made of pure carbon atoms arranged in a honeycomb structure. It is known to have a high electrical conductivity among other properties such as durability and flexibility.

‘We have shown that it is now possible to create cheap, sensitive and flexible photosensors from graphene alone. We expect our innovation will have great impact not only on the consumer imaging industry, but also in satellite imaging and communication industries, as well as the mid-infrared applications,’ said Wang.

‘While designing this sensor, we have kept current manufacturing practices in mind. This means the industry can in principle continue producing camera sensors using the CMOS process, which is the prevailing technology used by the majority of factories in the electronics industry. Therefore manufacturers can easily replace the current base material of photo sensors with our new nano-structured graphene material.’

If adopted by industry, Wang expects the cost of manufacturing imaging sensors to fall, eventually leading to cheaper cameras with longer battery life.

‘The performance of our graphene sensor can be further improved, such as the response speed, through nano-structure engineering of graphene, and preliminary results already verified the feasibility of our concept,’ Wang added.

This research, costing about $200,000, is funded by the Nanyang Assistant Professorship start-up grant and supported partially by the Ministry of Education Tier 2 and 3 research grants.

The next step, say the scientists, is to work with industry collaborators to develop the graphene sensor into a commercial product.

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