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Single molecule detection through a smartphone

a schematics representing a nano-antenna based on DNA in the center of the figure (with the DNA strand visible in the top section). On the left the molecules image captured with an electron microscope detecting the fluorescence. Image credit: Ludwig Maximilian University of Munich

Many diseases are characterised by the presence of specific molecules in body fluids. Searching for these molecules is challenging since there are billions of molecules in a sample and finding that specific one requires very sophisticated processes and equipments. Technicians in well equipped labs use chemical procedures to increase the number of these molecules or associate them to other molecules (like antibodies) that act as chemical searchers. When these “searchers” find their target the resulting chemical reaction  results in a change of some properties, like the emission of fluorescence, and this can be detected by a sensor. Here again, sophisticated detection equipment is usually needed.

Researchers at eh Ludwig Maximilian University of Munich are using DNA nanotechnology to create nano-antennas (see their representation in the figure) that can amplify the fluorescence signal. The DNA binds with tiny particles of silver and gold acting as light amplifiers. This allows the detection of specific bacteria and viruses, depending on the antibody used in the test.
According to the researchers in the future a device like a smartphone will be able, using its camera to detect the fluorescence, hence, together with a portable, mass market kit to perform the analyses, to detect the presence of a bacteria/virus. This may not be the final exam, but an important first level screening that in case it turns out a positive result will lead to a further test in a professional lab.

It is just one of several advances that by the end of this decade will support decentralised/tele-diagnoses changing the healthcare landscape.


About Roberto Saracco

Roberto Saracco fell in love with technology and its implications long time ago. His background is in math and computer science. Until April 2017 he led the EIT Digital Italian Node and then was head of the Industrial Doctoral School of EIT Digital up to September 2018. Previously, up to December 2011 he was the Director of the Telecom Italia Future Centre in Venice, looking at the interplay of technology evolution, economics and society. At the turn of the century he led a World Bank-Infodev project to stimulate entrepreneurship in Latin America. He is a senior member of IEEE where he leads the Industry Advisory Board within the Future Directions Committee and co-chairs the Digital Reality Initiative. He teaches a Master course on Technology Forecasting and Market impact at the University of Trento. He has published over 100 papers in journals and magazines and 14 books.


  1. Dear Professor, does the nano-antenna technology (luminous idea!) also lowers the energy needed to excite the fluorescence?
    Many thanks for the answer

  2. According to the article: “Interactions between the nanoparticles and incoming light waves intensify the local electromagnetic fields, and this in turn leads to a massive increase in the amplitude of the fluorescence” the nano-antenna is converting the energy of the the incoming light into fluorescence intensity (amplitude) via the electromagnetic field (the one that is actually intercepted by the nano-antennas). So my take would be that yes, you need less local energy to create luminescence but just because you tap onto the energy provided by incoming light…. No free lunch.