A nonlinear optical crystal chip that combines terahertz optical waves with microfluidic devices

Researchers from Osaka University have developed a non-linear optical crystal chip (NLOC) that combines terahertz light waves with microfluidic devices and takes full advantage of the close proximity of the terahertz source and the solution of the analyte in the microchannel. . Their research was published in the most recent issue of APL Photonics.

“Using this technology, even if the sample is less than one nanoliter, we can detect the concentration of several molecules of solution,” said Masayoshi Tonouchi, the correspondent. “This highly sensitive detection without labeling groups will be a low-intervention clinical option for the future.” Technology has very important prospects."

Fig.1 Schematic diagram of solution measurement using an assembled terahertz microfluidic chip

The chip includes a local terahertz radiation point source, a single microchannel, and an array of open resonant rings. A radiation beam from the back of the crystal activates the terahertz wave and interacts effectively with the flowing solution in the microchannel. At the same time, optical microscope imaging of fabricated terahertz microfluidic chips was also demonstrated.

The application of terahertz wave in biosensing has received much attention recently. Terahertz light waves have the ability to detect vibrations and rotations of molecules, and the intrinsic properties of the materials of interest to us can be measured without labeling groups.

However, until today, the diffraction limit of the terahertz wave and the superabsorbent nature of water still limit this technology. Microfluidic devices are a potential hope for analytical systems because the amount of sample required for measurement is small.

The early and rapid diagnosis of common diseases is one of the important application prospects of this technology in the future. The detection of cancer, diabetes, and influenza viruses requires only a small amount of body fluids, which greatly reduces the patient's detection process and pain. In addition, this technology can also analyze and detect living cells in a non-invasive way, which has many potential advantages for future research.

Fig. 2 Resonance frequency shift of mineral concentration in only 318 picoliters of mineral water

By observing the transformation of the resonance frequency of pure water, solute can be detected with an accuracy of up to 31.8 femtomoles.

The NLOC chip developed by Osaka University can generate terahertz radiation by itself and is closely connected with the microchannel device, which greatly improves its effectiveness. By comparing the frequency conversion of the existing ions of purified water and mineral water, the sensor chip can be used to analyze the concentration of minerals in the water. With this technology, the sensitivity can reach 31.8 femtomolars.

"Without the need for high-energy light sources or terahertz light sources, near-field probes or prisms, the high sensitivity of detection can be achieved, which provides multiple possibilities for future applications." Kazunori Serita, the first author of the paper, said, "For our research results in the future We are very excited about the potential application prospects, which has contributed to the rapid detection and compact device design in the future. It is particularly important that our findings are bound to accelerate the development and future of the terahertz lab chip technology."

This highly adaptable technology will surely affect many fields, such as analysis, biochemistry, cell biology, and clinical medicine.