Diamonds to track brain illnesses

By Anne Hansen

The goal of the DTU researchers is to develop two different sensors and integrate them on a chip that can be used to examine brain tissue and thus improve diagnosis of brain illnesses. In addition to being extremely sensitive and accurate, the new sensors will also function at ordinary temperatures and pressures. At the same time, they will be so robust that it will be possible to use them outside the hospital.

Diamonds—trackers of the future

When doctors are looking for traces of a disease or illness in the body, they often use an MR scanner. By measuring the magnetic fields generated by different types of body tissue, they can take detailed pictures and track illnesses in the brain, for example. Unfortunately, the very best magnetic field sensors—such as MR scanners—are extremely expensive and often only function properly under very special conditions.

Sensors made of diamonds, on the other hand, feature a range of advantages. For example, they are tiny, robust and relatively inexpensive, and they are so sensitive that they can register changes in the magnetic fields of individual cells. This means that these sensors can identify changes in tissue at a point when they may involve just a few cells.

“Diamond sensors are to be used, for instance, to perform extremely sensitive measurements of the brain which may well lead to improved diagnosis and provide us with a much better understanding of brain illnesses,” says Professor Ulrik Lund Andersen from DTU Physics, who is heading up the new research project.

Defective diamonds

An ‘inexpensive diamond sensor’ may sound like a contradiction in terms, but in this case the diamonds involved are absolutely tiny, measuring just a few microns (thousandths of a millimetre) in diameter. While the rest of us generally want big diamonds, the most important factor for researchers making sensors is the purity of the diamonds. 

 

A diamond sensor consists of ultra-pure diamond crystals that contain infinitesimally small defects—a nitrogen atom positioned where a carbon atom should be, for example.  The electrons around the nitrogen atom are extremely sensitive to external disturbances such as magnetic fields, and their condition can thus be used to measure changes in even very weak external magnetic fields. When the electrons are affected by a magnetic fields, they emit fluorescing light that a detector can then measure. The strength of the light is determined by the strength of the magnetic field which, in turn, is defined by the type of tissue or material in question. This means that diamond sensors can be used to produce pictures of tissues and materials accurate—at best—down to the positioning of the individual atoms.

Tiny diamonds of huge importance

The development of sensors that can measure tiny magnetic fields with nanometre accuracy, i.e. down to 10^-9 (0.000000001) m, constitutes a huge challenge in many areas of the natural sciences such as medicine, biology, chemistry and materials physics. Diamond sensors may thus come to play significant roles in areas as disparate as the measurement of geomagnetic fields and discovering hidden weapons and drugs. The development of sensors that can measure tiny magnetic fields with nanometre accuracy, i.e. down to 10 (0.000000001) m, constitutes a huge challenge in many areas of the natural sciences such as medicine, biology, chemistry and materials physics. Diamond sensors may thus come to play significant roles in areas as disparate as the measurement of geomagnetic fields and discovering hidden weapons and drugs.

Find out more about diamond sensors: 

Toward Molecular-Scale MRI, Science 1 February 2013, vol. 339, pp. 529–530

Find out more about the grant from The Danish Council for Strategic Research