An international consortium headed by researchers from the section for Quantum Physics and Information Technology, QPIT, and the DNRF center for macroscopic quantum states, bigQ, have recently demonstrated for the first time measurements of electrical activity in a mammalian tissue using a new type of microscope, based on quantum mechanical effects in diamond.
Quantum systems are often thought of as exquisitely designed and highly shielded systems involving ultra-low temperatures or complex optical systems, for which any disturbance from outside is highly undesirable. This is certainly true in the field of quantum computing, where one often encounters temperatures colder than space or ultra-clean optics.
However, this sensitivity to the environment can also be turned to an advantage, in making new, highly sensitive probes of factors such as temperature, electromagnetic fields or pressure. This new and rapidly growing field of quantum sensing promises sensors with capabilities and functionality well beyond anything possible today.
Funded by a grant from Novo Nordisk Fond, over the past 3 years, such sensors have been developed at DTU Physics based on quantum states hosted in solid state defects in diamond. These defects, consisting of missing and substitutional atoms called nitrogen-vacancy (NV) centres, offer extremely high sensitivity to both temperature and magnetic field. Unlike many quantum systems, they are robust and biocompatible, being able to touch living organisms and operate in solution, all at room temperature.
In their most recent work in collaboration with researchers at Copenhagen University and DTU Healthcare Technology, researchers at QPIT have used a magnetic field sensor based on NVs in diamond for in vitro study of electrical activity in a muscle. When stimulated by blue laser light, a biological action potential passes through the muscle, generating an electrical current and simultaneously inducing a magnetic field. By recording this magnetic field using the diamond sensor, they showed the shape and speed of the signal could be recovered.
“This offers new prospects of being able to map and measure electrical activity entirely passively in living subjects or microscopic dissections, without having to resort to invasive needle probes”, according to Dr Jim Webb and Luca Troise, the postdoctoral researcher and PhD student conducting the experimental work. “In the future, we hope to be able to map in realtime how signals propagate in the brain, allowing us new insights into neural structure, with possible application in new brain-computer interfaces”.
“The work represents a considerable step forward in the field, putting DTU at the forefront of research in the field of quantum biosensing”, according to Associate Professor Alexander Huck. “Quantum technology is a rapidly growing field and the applications of sensing, particularly biosensing, are significant for both research and the large biotechnology market in Denmark”, says Professor Ulrik Lund Andersen, the grant PI and section leader of QPIT
The work “Detection of biological signals from a live mammalian muscle using an early stage diamond quantum sensor” has been recently published in the Nature journal Scientific Reports (doi: 10.1038/s41598-021-81828-x).