MIT Scientists developed a Quantum Dot Spectrometer small enough to function within a smartphone

The scientists at Massachusetts Institute of Technology (MIT) created a Quantum Dot (QD) Spectrometer which is small enough to fit inside a smartphone camera. Spectrometers are the instruments that measure the properties of light.

The development was published on 2 July 2015 in the journal Nature and the lead author of the study is Jie Bao, a former MIT postdoc.

QD spectrometer represents a new application for quantum dots, which have been used primarily for biological molecules and labeling cells, as well as in television screens and computers.

Characteristic features of the device

• It is portable and would enable the devices to diagnose diseases, especially skin conditions, or detect environmental pollutants.
• It is about the size of a US quarter and deploys hundreds of quantum dot materials that each filters a specific set of wavelengths of light.
• It is unique and advantageous in terms of flexibility, simplicity, and cost reduction.

How it was developed?

In QD spectrometer approach, the scientists created the optical structure, i.e., QD filters by printing liquid droplets into a thin film and then placed it on top of a photodetector such as the charge-coupled devices (CCDs) found in cellphone cameras.

Then, the researchers created an algorithm to analyse the percentage of photons absorbed by each filter and recombined the information from each one to calculate the intensity and wavelength of the original rays of light.

The more quantum dot materials there are, the more wavelengths can be covered and the higher resolution can be obtained.

In this case, the scientists used about 200 types of quantum dots spread over a range of about 300 nanometres. With more dots, such spectrometers could be designed to cover an even wider range of light frequencies.

What are Quantum Dots?

Quantum dots (QD) is a type of nanocrystals which was discovered in the early 1980s. These are made by combining metals such as lead or cadmium with other elements including sulfur, selenium, or arsenic.

By controlling the ratio of these starting materials, the temperature, and the reaction time, scientists can generate a nearly unlimited number of dots with differences in an electronic property known as bandgap, which determines the wavelengths of light that each dot will absorb.

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