Mohali institute develops new laser tech for making nano-structures

Vijay Mohan

Tribune News Service

Chandigarh, May 26

Researchers at the Institute of Nano Science and Technology (INST), Mohali, have found a unique route to fabricate precisely controlled nanostructures of the desired geometry through a rapid one-step low power laser writing process. This has a huge potential in the fields of catalysis, sensing, and opto-electronic devices.

This will open up avenues in the detection capability of analytes and help shed new light in spectroscopy sensing of biological and chemical molecules. The technology can also be used in conjugation with an antibody for the spectroscopic detection of various biomarkers.

Present approaches to such fabrication involve the synthesis of complex morphologies, which limits their potential to be used for large area substrates. The INST is an autonomous institute under the Department of Science and Technology.

In order to overcome present limitations, the INST group developed a hybrid Surface Enhanced Raman Spectroscopy (SERS) platform using molybdenum disulfide nano-structures and gold nano-particles, where direct laser writing is used to engineer the artificial edges on the surface of the nano-structures.

This created localised hotspots with remarkable precision and control. SERS is a technique for molecular detection and characterisation that relies on the enhanced Raman scattering of molecules that are adsorbed on SERS-active surfaces, such as nano-structured gold or silver.

During the research, a focused laser beam of meagre power of a conventional Raman spectrometer was used for nano-structuring on 2D flakes of the desired size and geometry by just playing with the laser power and exposure time.

Producing SERS substrate of controllable hotspots distribution with the desired geometry and location is the main challenge. Several efforts have been made by researchers to attain the controllability over hotspots distribution via employing various synthesis procedures, hotspots engineering, defect engineering, etc. However, the random distribution of hotspots and precision over geometrical nanostructure has limited the progress in the field of SERS sensing.

The hybrid SERS platform developed by the INST group offers controlled formation of localised hotspots for ultra-sensitive and reproducible detection of analytes. Low power-focused laser irradiation technique was employed to create artificial edges on atomically thin 2D nano-structure sheet, which enables the superior deposition of gold nano-particles along the artificial edges. This enhances the local electromagnetic field leading to formation of hotspots.