A team of scientists at Nanyang Technological University (NTU) in Singapore has developed a new image sensor from graphene that promises to improve the quality of images captured in low light conditions. In tests, NTU claims it has proved to be 1,000 times more sensitive to light than existing complementary metal-oxide-semiconductor (CMOS) or charge-coupled device (CCD) camera sensors in addition to operating at much lower voltages, consequently using 10 times less energy.
The new sensor is able to detect broad spectrum light, from the visible to mid-infrared, with great sensitivity. This will make it ideal for use in all types of cameras, including infrared cameras, traffic safety cameras, satellite imaging, and more. According to NTU, this technology will allow photographers to take much clearer images in harsh lighting conditions and, when mass produced, estimates are that graphene sensors will be up to five times cheaper than camera sensors today.
The research was led by Assistant Professor Wang Qijie from NTU’s School of Electrical & Electronic Engineering and has been ongoing for two years. “We have shown that it is now possible to create cheap, sensitive and flexible photo sensors 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,” says Wang,
What is clearly exciting for the camera industry is how little needs to be done to introduce graphene to existing CMOS sensors.
“While designing this sensor, we have kept current manufacturing practices in mind," explains Asst. Prof Wang. "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 nanostructured graphene material.”
Graphene nano-structures
Graphene is a material composed of pure carbon with atoms arranged in a regular hexagonal pattern. It is a one-atom thick layer of the mineral graphite, a million times smaller than the thickest human hair and is known to have a high electrical conductivity and is very light, with a 1-square-meter sheet weighing only 0.77 milligrams.
Asst. Prof Wang has devised a novel way to create nanostructures on graphene which "trap" light-generated electron particles for a longer period of time, translating into a stronger electrical signal. These electrical signals are then processed into an image, such as a photograph captured by a digital camera.
The "trapped electrons" are the key to achieving high photoresponse in graphene, which makes it far more effective than the normal CMOS or CCD image sensors, said Asst Prof Wang. Essentially, the stronger the electric signals generated, the clearer and sharper the photos.
"The performance of our graphene sensor can be further improved, such as the response speed, through nanostructure engineering of graphene, and preliminary results already verified the feasibility of our concept," Asst. Prof Wang says.
Camera ISO
Why is this so exciting for the photography industry? Camera ISO is one of the three pillars of photography (the other two being aperture and shutter speed). In simple terms, ISO is the level of sensitivity of your camera’s image sensor to available light. The majority of people taking pictures have probably never adjusted the ISO setting on their cameras so here is an explanation. Essentially, a lower ISO setting reduces your cameras sensitivity to light creating higher quality images, while a higher ISO number increases sensitivity and your camera sensor can capture images in low-light environments without having to use a flash. But higher sensitivity comes at a cost – it adds grain or “noise” to the pictures.
Of course, not all grain is bad and we often see creative uses of it in black and white photography. But if you are a sports photographer shooting in a poorly lit indoor stadium, in order to freeze action, you have to shoot with a wide aperture (f 2.8 or lower) and try to keep your shutter speed above 500. The only way to do this is to increase ISO and live with the resulting grainy pictures. Asst. Professor Wang’s graphene sensor, being more sensitive, will negate the need to increase ISO in low light settings.
Canon and Nikon in particular, have been battling each other to develop the highest ISO levels with the least grain since the beginning of digital photography and no doubt “wires are buzzing" with these new developments. Asst. Prof Wang has already filed a patent through NTU’s Nanyang Innovation and Enterprise Office for his invention and plans to find industry partners to develop the graphene sensor into a commercial product. Our senses tell us that he won't have to look too far.
The NTU team's paper appears in the journal Nature Communications.
Source: NTU
In almost any camera/phone review I see example photos of the best the device can do but almost nobody ever does a good job showing the limitations of the device in poor lighting.
I walked into a photography store a while back and expressed my frustration at trying a decent camera for average lighting. The guy behind the counter handed me one and said "try this one".
I told my son to stand there and wave his arms around, and I took a photo of him in the middle of the mostly well lit store and there was a lot of motion blur. He didn't end up selling me the camera but it took me all of 5 seconds to effectively demonstrate the limitations of the technology which is something I rarely see in product reviews.
Benchmarking cameras based on optimal lighting means next to nothing in real world performance. Even putting a camera on a tripod to take pictures of fixed objects in a dimly lit room is a useless test because that's not how people use cameras and it allows the camera to compensate for low light sensitivity with a slower shutter speed without being penalized enough in motion blur.
I know fixed subjects like bowls of fruit make great apples to apples comparisons of cameras but unless we find better ways to benchmark light sensitivity we are going to be taking 40MP unusably blurry indoor photos years from now.
These innovations never see the light of day (pun intended). Why? Take your pick.
Until Canon or Nikon (or Sony or Panasonic) actually step up to the plate and claim "We are bringing to market this Fall a new camera that can shoot perfect photos in extremely low-light conditions and it will be called such-and-suchand cost X amount of dollars", then I am going to continue to shrug apathetically at these breakthroughs.
shall reserve my judgement until further tests are carried out since there's quite a lot of loop holes in this article. it's a good start though!
@ Siegfried Gust: Yeah, that's exactly what I was thinking. Still, unlike many pro cinema cameras, still photography cameras seem to all set their optimal gain at ISO 100-400 no matter how great they perform at the higher numbers. The 1D X, the best low-light camera on the market right now, still produces better images at ISO 100 than at 1600, even if 1600 is startlingly clean. For video, hopefully manufacturers get creative with implementing in-built ND filters... I hear the new Red Dragon sensor will have a native ISO of 2000...
@ thk: Well, since a stops of light are factors of two, 1000x more light would mean a difference of about ten stops. Ten stops is the same difference between ISO 100 and 102,400, so yeah, that's a lot of light.
@ Rolf Hawkens: Especially what with how conservative many of the larger camera companies are with advancements in product capabilities, I wouldn't put it past some of them to take much, much longer than necessary to release products with this technology, were they to license it.
DonGately, color is done the same way it is with every camera. Read Wikipidia.
Siegfried Gust, if you have too much light sensitivity the answer is very simple and old, a light filter. I think this one is called a graduated neutral density filter.