One of the biosensing methods is based on changing the frequency of laser.
In this method, the laser light illuminates the biomarkers and interacts with them. The interaction changes its frequency or color. This change indicates the presence of a biomarker, namely a low-cost, noninvasive method that results in the detection of molecules indicating the presence of a disease.
Unfortunately, these optical sensors could not be integrated on small photonic chips because of the complex geometries and lack of robustness of configurations. Now scientists have solved this problem with aluminum oxide which doped with ytterbium.
Researchers from the University of Twente, Netherlands, have used a chip-based optical sensor with a laser integrated into it to detect a cancer biomarker called S100A4 in a urea sample. This new optical sensor, which is more sensitive than previous ones, by detection of the S100A4 protein that indicates tumor development, paves the way for faster and more sensitive detection of biomarkers. As a result, treatment is faster. The color or frequency of laser light changes dramatically as a result of the interaction with S100A4.
Aluminum oxide with ytterbium, has a low optical loss and a range of 1020 to 1050 nanometers, outside the absorption band of water. The researchers were able to measure the protein at a concentration of 300 pM in urea, which demonstrates the potential of the proposed device for biosensing.