Quantum Dot Tattoos

On one application of the technology that won this year's Nobel Prize in Chemistry

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This year, the Nobel Prize in Chemistry went to Moungi Bawendi, Louis Brus and Alexei Ekimov for discovering and developing quantum dots, tiny particles of semiconducting material. These dots, only 2-10 nanometers across, contain under 100 atoms: often, only 10 to 50. They can transport electrons and emit light when exposed to UV radiation. They act as a single entity, embodying the properties of one atom even though they are composed of dozens, which allows for scientists and engineers to fine-tune their light-emitting properties.

Since their discovery in the 1970s, the quantum dot has transformed an array of products and use cases: Solar panels. Lightbulbs. TV screens. Quantum computers. Drug delivery. Neural imaging. And vaccination.

Developing nations often lack a robust infrastructure or central database to store medical records. In turn, it’s hard to determine who needs what vaccine, especially for vaccines (like MMR — measles, mumps, and rubella) that require multiple doses spread out over a specified time interval. Without accurate records, patients may not receive all necessary doses.

Enter quantum dots.

In 2019, a team of scientists at MIT — led by Kevin McHugh — decided that, rather than storing vaccine information in a central database, it should be stored with each person. Or, rather, in each person using quantum dots.

McHugh and his team developed a copper-based quantum dot — only about 4 nanometers across — that would be injected into a person, right below their skin, via a microneedle patch. Microneedle patches are being developed to deliver vaccines like MMR, and McHugh demonstrated that his quantum dots could be easily incorporated into these vaccine patches.

Quantum dot tattoo technology (source: MIT)

Thus, when you get the vaccine, you also get a quantum dot record of what vaccine you just received. For each vaccine, there will be a special pattern of quantum dots that goes with it. Like a secret QR code for your vaccine record.

The dots are invisible to the naked eye, but they can be viewed using modified smartphones. They last for up to five years, so someone can scan a patient’s arm and see what vaccines they’ve received. As the team wrote in their paper on the invention: “By codelivering a vaccine, the pattern of particles in the skin could serve as an on-person vaccination record.” All thanks to some tiny balls of copper atoms.

Quantum dot tattoo patterns (figure from original paper in Science, 2019)