The world’s smallest silicon LED could turn your phone into a high-power microscope

Researchers at the Singapore-MIT Alliance for Research and Technology (SMART) have developed a new silicon Light Emitting Diode (LED) and holographic microscope which between them could help turn your smartphone into a powerful, high-resolution microscope. Together they are both the world’s smallest LED and the world’s smallest holographic microscope.

This LED, they say, is comparable in output to much larger silicone LEDs. But, by “much larger”, we’re not talking huge. Remember, this is the world’s smallest silicon LED and it’s very small indeed. Smaller than the wavelength of light itself.

The LED was used to develop the world’s smallest holographic microscope as a proof of concept. The idea is that it enables cameras in existing devices such as smartphones to become high-resolution microscopes, simply by modifying the silicon chip and software. It’s complemented by a new neural networking algorithm – AI had to be in there somewhere, right? – developed by SMART which is able to reconstruct the objects measured by the microscope.

Study Abstract:

A nanoscale on-chip light source with high intensity is desired for various applications in integrated photonics systems. However, it is challenging to realize such an emitter using materials and fabrication processes compatible with the standard integrated circuit technology. In this letter, we report an electrically driven Si light-emitting diode with sub-wavelength emission area fabricated in an open-foundry microelectronics complementary metal-oxide-semiconductor platform. The light-emitting diode emission spectrum is centered around 1100 nm and the emission area is smaller than 0.14 μm2 (~∅400 nm). This light-emitting diode has high spatial intensity of >50 mW/cm2 which is comparable with state-of-the-art Si-based emitters with much larger emission areas. Due to sub-wavelength confinement, the emission exhibits a high degree of spatial coherence, which is demonstrated by incorporating the light-emitting diode into a compact lensless in-line holographic microscope. This centimeter-scale, all-silicon microscope utilizes a single emitter to simultaneously illuminate ~9.5 million pixels of a complementary metal-oxide-semiconductor imager.

The applications for the technology are quite wide-reaching in a number of fields. The researchers say that it would allow (very) close-up inspection of plant seeds and tissue samples straight from your smartphone. It would also allow enhanced microscopic inspection of previously impossible objects and the detection of plant disease and aberrant plant tissue. Again, it’s your smartphone. So, you’d be able to inspect objects anywhere. You wouldn’t need to chop samples off and send them to a lab for examination.

If you want to find out more about the research, the complete study has been published on Optica, and it’s a fascinating, albeit complex, read.

[via Interesting Engineering]