Nanosensors for biomedical applications

At Fraunhofer IMS, we develop biofunctional sensors for applications in medical diagnostics. We use semiconducting carbon nanotubes (single-walled carbon nanotubes, SWCNTs) that fluoresce in the near infrared (NIR, 870-2400 nm). Unlike other fluorophores, they do not bleach, which makes them ideal for long-term monitoring.

Our sensor technology is based on changes in the molecular environment of one-dimensional nanomaterials. The sensors can be assembled in a modular fashion.

In addition, the surface of the nanotubes is highly sensitive to changes in their environment. Through clever design, sensors can be created for a wide range of analytes. Our applications range from the spatially and temporally resolved detection of neurotransmitter release and the detection of the SARS-CoV-2 spike protein to the detection of bacteria in culture supernatants and the monitoring of enzymatic reactions.

We are constantly working on innovative approaches to improve the performance of our sensors. This includes modifying the sensors with so-called quantum defects, which can be imagined as small irregularities in an otherwise perfectly structured material.

By introducing such irregularities in a controlled manner, the optical properties can be controlled and optimized for various applications. For example, it is possible to modify the fluorescence of the nanotubes by changing their absorption and emission wavelengths and to increase the quantum efficiency, i.e., the intensity of the fluorescence.

The introduction of defects furthermore allows us to functionalize nanosensors with detection units and to control the selectivity of one-dimensional nanosensors by structuring the surface at the molecular level.

The optical detection of signals in the near-infrared (NIR) spectral range (780-2400 nm) enables particularly interference-free readouts through biological tissue and fluids in biomedical contexts, characterized by high signal-to-noise ratios and deep penetration depths.

In order to detect and image the signals from optical sensors, we at Fraunhofer IMS develop innovative setups that enable you to read signals in the NIR range.

These systems include compact readout devices for the spectral range > 900 nm and hyperspectral setups that can generate rapid hyperspectral (NIR) images with only three images, as well as the modification of standard microscopes for the NIR range.

Hyperspectral imaging with three images

Hyperspectral imaging captures both spectral and spatial information. Our HyperNIR module requires only three images and generates spectral information in the range between 900 nm and 1600 nm. Spectral resolutions of less than 5 nm and frame rates of 0.2 frames per second are achieved using the full camera resolution.

This user-friendly technology enables simple hyperspectral imaging, whereby any standard camera for the NIR range can be upgraded to a hyperspectral camera using the HyperNIR module. This allows us to access wide range of biomedical imaging and environmental monitoring applications.