New sensor could lead to low-cost medical imaging and night vision using smartphones and cameras

May 26, 2014

SEM image showing C60 nanorod photoconductor fabricated by depositing C60 nanorod film onto pre-patterned gold electrodes. Inset: SEM image showing C60 nanorods bridging 10-micron-wide electrodes. (Credit: Rinku Saran et al./Scientific Reports)

Low-cost medical and security cameras could be possible in the future thanks to a new multispectral light sensor developed by University of Surrey researchers. The sensor can detect the full spectrum of light, from ultraviolet (UV) to visible and near-infrared light.

“Until now … multiple sensors were required to measure different ranges of the light spectrum, significantly increasing cost,” said lead researcher Richard Curry, PhD. from the University of Surrey’s Advanced Technology Institute.

The innovation was enabled by the use of C60 (fullerene) nanorods, which have unique optoelectronic properties, including high electron mobility, photosensitivity, and conductivity. They also allow for large-scale synthesis at room temperature, so the sensors can be produced cheaply, using conventional laser-printers, and do not require specialized manufacturing conditions. The sensors are also flexible.

The near-infrared capability could one day allow surgeons to use lower-cost devices to view tumors prior to surgery and could lead to low-cost consumer products, such as cameras and smartphones, that will be able to monitor blood or tissue oxygenation level or capture high-quality pictures in the dark. (Near-infrared is already commonly used in more-expensive security camera systems and for quality control in the agriculture and food industry.)

A paper on the research was published Friday in Nature’s Scientific Reports (open access).

Abstract of Scientific Reports paper

One dimensional single-crystal nanorods of C60 possess unique optoelectronic properties including high electron mobility, high photosensitivity and an excellent electron accepting nature. In addition, their rapid large scale synthesis at room temperature makes these organic semiconducting nanorods highly attractive for advanced optoelectronic device applications. Here, we report low-cost large-area flexible photoconductor devices fabricated using C60 nanorods. We demonstrate that the photosensitivity of the C60 nanorods can be enhanced ~400-fold via an ultralow photodoping mechanism. The photodoped devices offer broadband UV-vis-NIR spectral tuneability, exhibit a detectivitiy >109 Jones, an external quantum efficiency of ~100%, a linear dynamic range of 80 dB, a rise time 60 µs and the ability to measure ac signals up to ~250 kHz. These figures of merit combined are among the highest reported for one dimensional organic and inorganic large-area planar photoconductors and are competitive with commercially available inorganic photoconductors and photoconductive cells. With the additional processing benefits providing compatibility with large-area flexible platforms, these devices represent significant advances and make C60 nanorods a promising candidate for advanced photodetector technologies.