Researchers create new optical biosensor to detect cancer

Biosensors are important diagnostic devices that have to be quick, cheap, and easy to use. It's also beneficial if biosensors are compact and autonomous so they can be used by anyone from doctors down to the patient themselves. Most optical biosensors require a wide range of light colors, like a rainbow, to operate reliably.

The need for a wide range of light makes the sensors bulky, expensive, and more sophisticated. Most biosensors available today require a spectrometer to extract the most precise data from each light color, limiting their use. Scientists at EPFL have introduced a new concept that allows a single light color to operate as a simple imaging detector. Despite using only a single color of light, the system provides extremely accurate bio-sensing information as if the entire rainbow of light colors illuminated the sensor.

The new biosensor uses two specific functions including nanophotonics and data science techniques. The chips themselves are constructed out of nanostructures made from silicon. Nanostructure silicon surfaces have features in the order of 100 nm to trap light on the biosample/chip interface more efficiently. That makes biosensors extremely sensitive to the presence of biomarkers resulting in distinct changes in incident light features.

That feature is the change in the "amount" of collected light known as light intensity. Typically, the camera continuously receives the light that passes through the biochip to acquire images from the biochip with intensity information over millions of image pixels. Biomarkers attached to the nanostructures on the biochip and intensity change images are compiled from the induced intensity change of each pixel at very high resolutions.

The researchers leveraged a data science technique in combination with a prerecorded performance map to process light intensity information from the large number of pixels. The system considers each pixels efficiency and adjusts its contribution to the final readout in a collective manner. Researchers liken the process to making a solid conclusion after receiving input from a group of experts by weighing their knowledge of the field carefully.

Scientists on the project created a demonstration that use the new biosensor for cancer diagnostics to detect tumor exomes, which are early-stage cancer biomarkers. The team determined that the image-based biosensor could monitor in real-time breast cancer exomes over an extensive detection range, making them clinically relevant for both healthy and sick individuals.