Tiny lens that uses light trickery to detect gas created in Germany

A research team from the University of Jena has developed a tiny optical lens, just a few millimeters in size, that can change its refractive behavior in the presence of gas.

The researchers describe the microlens’s ability to change its refractive behavior as “intelligent.” This feature is made possible by the hybrid glass material from which the lens is made. The lens is uniquely designed with a three-dimensional lattice containing cavities.

These cavities can accommodate gas molecules, which is likely to affect the optical properties of the material.

Developing multi-responsive materials with the Carl Zeiss Foundation

Lothar Wondraczek, Professor of Glass Chemistry at the University of Jena shares that the Carl Zeiss Foundation has been helping them in their efforts. With the Foundation’s help, they are now developing multi-responsive materials.

“In the case of the hybrid glass lens, this means that it refracts light more or less strongly depending on whether gas is absorbed in the lens material”, he said. However, no effort comes without challenges. In this case, it was to transfer classical glass-forming methods to these special materials.

The group of researchers had been teaming up with Dr Alexander Knebel to develop a suitable synthesis process for highly pure materials. This was followed by identifying the optimal conditions to shape the material.

The chemists revealed that they melted the material, then transferred it into a 3-D printed mould and pressed it. They chose the shape of the lens deliberately, because “even the smallest impurities are noticeable in a lens as they directly affect the optical properties,” explained one of the chemists.

Wondraczek added that the metal-organic frameworks used there were researched and developed as materials for gas storage or separation. The researchers shared that most of these substances decompose when heated, and thus are pretty difficult to form.

Advancing multi-responsive materials for enhanced sensor technology

This new process can allow a wide variety of shapes and geometries. It will allow extending beyond the specific application as microlenses. Wondraczek shared that since these are multi-responsive materials, they can react to multiple influences simultaneously.

“They could be used for logical circuits , for example. This specifically means that two conditions are linked for the observable reaction,” he explained .

“If a light beam hits the lens and gas is absorbed in the lens material simultaneously, then the light is refracted in a particular way, providing combined feedback.”

This discovery seems to be a ground breaking one since leakages in industrial production processes has always been a concern of safety. In the past, there has been the emergence of cameras like The InfiRay G600 Uncooled Infrared Camera. These cameras can significantly help in tackling and detecting leaks from different sources.

These include leakages of natural gas, refrigerant, ammonia, sulphur hexafluoride, and lots more poisonous gases. These cameras are equipped with the latest technology like high-definition infrared detection, extensive gas species detection, sensitivity and spatial resolution.

For all these reasons it’s pivotal to develop such devices which can add to safety and prevent mishaps. In this case, the researchers say that membranes for gas separation are also conceivable. These membranes are those whose optical properties change in the presence of gas molecules.

Some of these components could be used in sensor technology, thereby more efficiently and intelligently making measurement methods.

The research was published in the journal Nature Communications .

Abstract

Hybrid glasses derived from meltable metal-organic frameworks (MOFs) promise to combine the intriguing properties of MOFs with the universal processing ability of glasses. However, the shaping of hybrid glasses in their liquid state – in analogy to conventional glass processing – has been elusive thus far. Here, we present optical-quality glasses derived from the zeolitic imidazole framework ZIF-62 in the form of cm-scale objects. These allow for in-depth studies of optical transparency and refraction across the ultraviolet to near-infrared spectral range. Fundamental viscosity data are reported using a ball penetration technique, and subsequently employed to demonstrate the fabrication of micro-optical devices by thermal imprinting. Using 3D-printed fused silica templates, we show that concave as well as convex lens structures can be obtained at high precision by remelting the glass without trading-off on material quality. This enables multifunctional micro-optical devices combining the gas uptake and permeation ability of MOFs with the optical functionality of glass. As an example, we demonstrate the reversible change of optical refraction upon the incorporation of volatile guest molecules.