A multi-purpose sensor based on an exclusively designed gold film has been created by researchers from the Far Eastern Federal University (FEFU) in collaboration with colleagues from Russia, Australia, and Japan, where the surface of the gold film is distributed with millions of parabolic nanoantennas.
The researchers achieved this using femtosecond laser printing. The sensor identifies molecules at trace concentration in gas and liquid environments. It can be easily modified to offer various modalities such as medical, biological studies and security tasks.
The associated research has been reported in the Nanomaterials journal.
The sensor reacts to the smallest variations in the surroundings in the vicinity of its surface, for example, gas or organic molecules, variations in the local refractive index of a liquid, etc. It can be applied for food quality analysis, bioanalysis, environmental monitoring, and different security systems.
Despite the significant progress that science has made in the field of high-precision physicochemical sensors over the past several decades, flexible inexpensive technologies for manufacturing cheap multi-purpose sensors combining different measurement modalities within single device are still required. Existing lithographic technologies for such sensors fabrication are time and money consuming and therefore are not suitable for mass production.
Aleksandr Kuchmizhak, Research Fellow, Virtual and Augmented Reality, FEFU STI
Kuchmizhak continued, “We proposed efficient and cheap laser printing technology to solve the mentioned issue. Using it we can easily produce sensor elements with the desired surface morphology and resonant properties, optimized to merge different sensing modalities and, to have sufficient mechanical strength to operate in liquid environment.”
The sensor system, which is based on nanotextured gold film, was developed through direct femtosecond-laser printing. When such an ultrathin gold film was exposed to single femtosecond pulses, millions of hollow parabolic nanostructures (nanovoids), the so-called nanoantennas, were formed.
An ordered array of these nanostructures exhibits marked resonant optical properties. They effectively change incident radiation of the visible and IR spectral ranges into unique surface waves, the so-called surface plasmons, which offer the sensor with its incredible sensitivity to variations in the surroundings.
Researchers from FEFU, FEB RAS, and MEPhI, as well as from Tokai University (Japan), Nagoya Institute of Technology (Japan), and Swinburne University of Technology (Australia) contributed to the study.
Earlier, researchers from FEFU and Swinburne University of Technology collaborated with Indian and Japanese colleagues to create an optical element based on an array of cross-shaped silicon nanoantennas.
Since these nanoantennas are arranged in a suitable way, they formed a spiral waveplate for THz and middle-IR spectral ranges, thus enabling an ordinary Gaussian beam to be changed into a singular vortex beam. The optical element was developed with the aim of performing advanced laboratory studies of the structure of proteins in IR spectral range, as well as for exploring new chiral molecular compounds.
This study was supported by the Russian Science Foundation through the grant No. 16-12-10165.