Sensors are essential tools in variety of disciplines ranging from biology and medicine to engineering. There are variety of sensors available such as magnetic, thermal and mechanical sensors in which the function of the device is based on the changes in their magnetic, thermal or mechanical response. Optical sensors are another class of sensing systems that works through the changes of the optical response upon application of an external drive. Plasmonic materials are one of the extensively used platform for optical sensor application. Generally the optical response of any plasmonic material changes when for instance the refractive index of the surrounding environment or the distance between the plasmonic sustaining elements (unit cells) of the sensor changes. Hence, implementation of plasmonic materials for sensing purposes is rather straightforward and the only challenge would be the fabrication of the plasmonic materials. The other big problem in sensors is the read-out platform. In other words, the miniaturization of sensors are hindered because of the bulky read-out systems. For instance, optical sensors mainly needs light generators and detectors which are not only very expensive but also big and bulky.
In another post (link) dewetting process was introduced as an easy method for development of the plasmonic material. The question might arise how to make a sensor out of plasmonic materials without traditionally complicated read-out. The answer is very simple. The discontinuous film composed of nanoparticles which can be developed by dewetting can perform as a gas sensor for detection of variety of gasses. If this sensor exposes to air the optical resonance can locate in green part of spectrum while exposure of the system to another gas (e.g. acetone) shifts the response to red part of spectrum. Therefore, the color of the film changes by changes of the environment which means that there is no need for design and fabrication of read-out system. Visually one can recognize and sense the changes of the environment by checking the color of the film.
Very simple ideas can turn to great triumphs!