Sensor chip to measure chemicals
11 Jun 2014
University develops minute chemical sensor on a chip which uses infrared laser beams and light detectors.
Scientists at the Vienna University of Technology (VUT) have developed a miniaturised infrared laser beam technology, capable of measuring chemicals within liquid and gas, and implemented it in the prototype for a new type of sensor.
The finding are published in the journal Nature Communications.
The chip features specially designed quantum cascade lasers and light detectors which are created by the same production process.
“As both parts are created in one step, laser and detector do not have to be adjusted
Benedikt Schwarz
The gap between laser and detector is only 50 micrometres and is bridged by a plasmonic waveguide made of gold and silicon nitride.
Quantum cascade lasers, unlike their ruby-red counterparts, are made of an optimised layer system of several different materials.
That way, the properties such as the wavelength of the laser can be tuned. When a voltage is applied to the layer structure, the laser begins to emit light.
Similarly, the structure can also work the other way around - when it is irradiated with light, an electric signal is created.
Scientists at VUT have now managed to create a laser and a detector at the same time, on one single chip, in such a way that the wavelength of the laser matches the wavelength to which the detector is sensitive.
“As both parts are created in one step, laser and detector do not have to be adjusted. They are already perfectly aligned”, said Benedikt Schwarz of the VUT research team.
The sensor chip system works by being submerged in a liquid.
By measuring the decrease of the detected light intensity due to the presence of light absorbing molecules, the composition of the liquid can be determined, research suggests.
To accurately judge its capabilities, the sensor was tested with a mixture of water and alcohol. The water concentration can be measured with an accuracy of 0.06%.
