Metamaterials are composite materials that derive their properties from internal microstructure rather than chemical composition found in natural materials. This special material is normally made of microscopic-sized assemblies of multiple materials, including metals and plastics arranged in repeating patterns.
Infrared spectroscopy is a technique that identifies components based on patterns of reflected light by measuring the properties of molecules to absorb infrared of their intrinsic frequencies. Each substance has its unique light-absorbing characteristics so that scientists can recognize the types.
If only small traces of the target substance are detected, the results will not be as significant due to the small difference in light intensity.
Scientists at UNIST have now come up with a new metamaterial that is highly efficient and can be mass-produced for a low price. The main feature of this metamaterial is that it improves the sensitivity of infrared absorption spectroscopy more than 100 times.
Further, it can be used to create ultra-sensitive infrared sensors to detect biomolecules and harmful substances. Also, it is cost-effective and easy to make.
Scientists created the metamaterial using crisscross layers of nanoantennae in a metal-insulator-metal configuration to have vertical nano-sized gaps of a smaller size than the infrared wavelength. Each layer is 10-nanometer thick.
UNIST researcher Hwang In-Yong said, “The proposed metamaterial achieved a record-high difference of 36 percent in our demonstration on a monolayer with a thickness of 2.8 nanometers. This is the best record achieved to date among monolayer detection experiments. Conventional metamaterials require expensive high-resolution lithography machines to produce microstructures on the material’s surfaces, but KIMM’s production stages involve affordable nanoimprint lithography and dry-etching processes to cut manufacturing costs.”
- Inyong Hwang et al. Ultrasensitive Molecule Detection Based on Infrared Metamaterial Absorber with Vertical Nanogap. DOI: 10.1002/smtd.202100277