- Applications abound for newly licensed microLEDs
LAURA S. MARSHALL, LAURA.MARSHALL@PHOTONICS.COM
STRATHCLYDE, UK – Communications and life sciences can expect
a boost from a newly formed company in Glasgow.
In a spinout deal, the University of Strathclyde has formed mLED
Ltd., a company dedicated to promoting its newly licensed microLEDs, dense arrays
of up to several thousand miniature light sources per square millimeter. The arrays
are pattern-programmable and do not require a plethora of external components –
such as optics or switching matrices – to modulate the light pattern. This
makes them more efficient and compact than other, similar technologies.
Shown is the array of microLEDs licensed by mLED.
“The LEDs give out light by electroluminescence upon injection
of an electrical current in exactly the same way as conventional large-area LEDs
familiar in indicator lamps, traffic lights and moving message displays,”
said professor Martin Dawson, director of research at the university’s Institute
of Photonics. “Because of their small size, however, they emit light at high
optical power densities and can be switched at very high speeds.
“The light pattern is produced by direct electrical control
of the individual microLED elements and, therefore, does not rely on switchable
polarizers or mirrors, as is the case in liquid crystal displays or digital light
projection systems, for example.”
In this 64 x 64 green matrix-addressed array, each LED pixel is 20 μm in diameter.
The devices are compatible with silicon CMOS electronic control,
Dawson added, enabling different modulation as needed for specific applications
and allowing for integrated photodetection to be used in optical microsystems.
“In communications, the devices can be modulated at data
rates up to 1 GB/s per pixel and can be used in free-space visible light communications
or polymer optical fiber communications,” he said. “They also offer
the prospect of photopumping organic semiconductor lasers integrated on-chip.”
Mask-free photolithography and UV direct writing make up other
areas where microLEDs could prove beneficial.
“Projecting the array optical patterns into photoresists,
for example, allows semiconductor microfabrication without mask aligners and hard
customized optical masks,” Dawson said. “Indeed, we are now using the
microLED arrays in this way to produce new microLED arrays.
“In the life sciences, the technology is very suitable for
integrated lab on a chip. For example, the arrays can produce light-patterned electrode
structures suitable for ‘optoelectronic tweezers,’ enabling manipulation
of cells or microparticles on-chip. In fast-pulsed operation, in conjunction with
photon-counting electronics, they can be used for highly parallel, on-chip, time-resolved
Optogenetics research and the development of retinal prosthetics
also could benefit from microLEDs, he said. “The devices also have implications
for microscopy, where sequential scanning of special striped format microLEDs
can allow wide-field depth-sectioned images of biomaterials to be obtained.”
The technology was developed at the Institute of Photonics, and
the researchers involved – Dawson; Dr. Erdan Gu, associate director; and Dr.
Gareth Valentine, research technologist – will act as consultants to mLED.
Dawson noted that they have been working on the topic since 2001.
Left to right: Dr. Jim Bonar, chief executive of mLED Ltd.; professor Martin Dawson, director of research of the Institute of Photonics at the University of Strathclyde; and Dr. Erdan Gu, associate director
of the institute, with the array of microLEDs licensed by mLED. Images courtesy
of the University of Strathclyde and mLED Ltd.
Funding for the new company was led by Braveheart Investment Group,
investing via the Strathclyde Innovation Fund and the Alpha EIS Fund. Additional
funding came from Scottish Enterprise’s Scottish Seed Fund.
“MicroLEDs have particularly strong potential for evolving
life science markets such as neuroscience and for the emerging telecoms market of
pico projectors, as well as for printing, microscopy and next-generation general
lighting arrangements,” said Dr. Jim Bonar, chief executive of the new company.
“We have easy-to-use, turnkey demonstrator kits available
for sale so that developers can see if the microLEDs fit with their own innovative
applications. The stand-alone graphical user interface permits simple and effective
control of the microLED platform,” he noted, adding that mLED has already
begun shipping products to customers.
“Research in new areas will carry on, and we look forward
to working with mLED in bringing this advancing technology to rapidly expanding
marketplaces,” said Simon Andrews of the Institute of Photonics.
- The nonthermal conversion of electrical energy into light in a liquid or solid substance. The photon emission resulting from electron-hole recombination in a PN junction is one example. This is the mechanism employed by the injection laser.
- In general, changes in one oscillation signal caused by another, such as amplitude or frequency modulation in radio which can be done mechanically or intrinsically with another signal. In optics the term generally is used as a synonym for contrast, particularly when applied to a series of parallel lines and spaces imaged by a lens, and is quantified by the equation: Modulation = (Imax – Imin)/ (Imax + Imin) where Imax and Imin are the maximum and minimum intensity levels of the image.
MORE FROM PHOTONICS MEDIA