A new invisible 'tattoo' allows medical information to be stored subcutaneously. The data can be read using a customised smartphone, making it always available to doctors and caregivers.
The storage method was developed by researchers at MIT, who describe their findings in Science Translational Medicine. Worldwide, 1.5 million deaths are preventable by vaccinations every year. Especially in developing countries, lack of vaccinations causes many deaths. Vaccination campaigns in developing countries are often challenging as there is little or no infrastructure available for storing medical data.
Who gets which vaccine?
This presents challenges. For instance, the lack of such infrastructure makes it difficult to track who needs a specific vaccine. In addition, many vaccines require multiple doses, to be administered at specific times. Without accurate vaccine registration, it is not possible to ensure that all children receive the necessary doses.
The researchers aim to change this with their new storage method. The method stores data in a subcutaneous ink cartridge, which is invisible to the naked eye. "In areas where paper vaccination cards are frequently lost or not used and electronic databases are not present, this technology can enable rapid and anonymous detection of a patient's vaccination history to ensure that every child has been vaccinated," says Kevin McHugh, assistant professor of biosciences at Rice University and former MIT student.
Quantum dots
The ink in which data is stored has nanocrystals, also known as quantum dots. The quantum dots emit near-infrared light. This light can be captured using a prepared smartphone, with its infrared filter removed. Tests with simulated sunlight show that the ink remains detectable under the skin for up to five years.
A patch fitted with microscopic needles applies the ink subcutaneously. These needles feature a combination of soluble sugar and a polymer called PVA. Once the patch is on the skin, the 1.5-millimetre-long micro-needles partially dissolve, releasing the ink within two minutes. By targeting ink in certain micro-needles, it is possible to create a pattern that remains subcutaneously.
Bundling with vaccines
Such a patch is also a widely used method for administering vaccines. The researchers expect to be able to bundle their recording method with these vaccines, thus avoiding the need for patients to be pricked extra, for example.
The researchers claim that the subcutaneous use of quantum dots is safe as the quantum dots are incorporated into biocompatible polymer. Further studies on the safety of the method are planned in the near future.
VeriChip
Using a subcutaneous chip to access medical information is not new, by the way. For example, in 2004, the US Federal Drug Agency (FDA) approved the use of a chip to facilitate access to electronic patient records. This chip is called the 'VeriChip' and was developed by US company Applied Digital Solutions. The chip contains a unique 16-digit code linked to the patient. By reading this chip, doctors and healthcare providers can access the patient's medical record via the internet.
Microsoft entered into a partnership with VeriChip Corporation, a subsidiary of Applied Digital Solutions, in 2008. This involves integrating Microsoft HealthVault's web-based personal medical record with VeriChip's VeriMed RFID tag. Doctors using a scanner to scan this VeriMed tag were thereby given access to the patient's medical data in Microsoft HealthVault. The service was launched in the Netherlands in 2014, but has not been available since November 2019.
Author: Wouter Hoeffnagel
