Sensor measures individual particles in a blood sample

Blood contains several hundred different proteins that give an indication of general health, providing information about the condition of our heart or the presence of cancer.

Currently, when doctors are given a blood sample for a comprehensive check, it can only be analysed for five or six indicators such as blood percentages, blood sugar and infections. For other test results, the sample must be sent to a laboratory for analysis and it can take up to a week before the results come back.

Four years ago, SINTEF began a joint project with Stanford University and the University of Oslo (UiO). The aim was to build a sensor that could improve sensitivity by a million-fold, making it possible to measure individual particles in the blood, including proteins at extremely low concentrations, as well as DNA and RNA (ribonucleic acid) molecules.

The result is a new nanoparticle sensor developed in MiNaLab in Oslo that comprises a thin silicon membrane perforated with hundreds of small holes arranged in a regular pattern.

‘We call these structures photonic crystals; the same structures occur naturally in the wings of some butterflies,’ said researcher Ib-Rune Johansen from SINTEF ICT.

One of the properties of the crystal is that it amplifies parts of the light spectrum.

Johansen said: ‘When we are looking for particles in blood samples, we illuminate the photonic crystal from behind. That way, we can amplify the intensity of light within the membrane by many hundred-fold.

‘The crystal is impervious to light: all light is reflected and nothing gets through. Viewed from behind, therefore, the crystal looks like the dark night sky.

‘However, each particle that is captured becomes trapped in a hole in the membrane and allows some light to leak through — giving it the appearance of a star in the sky. Our breakthrough came with this opportunity to see these microscopic particles.’

Detecting imbalances

Currently, medical laboratories measure proteins to detect imbalances in the body that occur when an infection is present and the new sensor is claimed to take these analyses further.

To this end, SINTEF’s chemists are trying to attach receptors to the wall of each of the perforations in the membrane.

When blood is pumped through, the receptors trap very specific molecules, depending on what the scientists are looking for.

Because the sensor/membrane has many perforations, they can specify a wide range of different proteins.

It will thereby be possible to detect illnesses such as prostate and ovarian cancer in their very early stages.

The researchers have also discovered a high-specificity method, as well as their exceptional specificity method. Patent applications have been filed for both discoveries.