Abstract:

Nowadays, the society is suffering a global world crisis due to the SARS-CoV-2 pandemic. To fight this health emergency, it is crucial not only the development of vaccines and drugs but also the use of technological devices. An example of these are infrared (IR) thermometers, which are mainly used for non-contact temperature measurement.
Despite their widespread use in the current situation, students are not used to knowing the basic principles of its operations. Hence, it is of utmost importance to approach undergraduate students to a practical example of a device they can find almost everywhere.

It is a fact that science is interconnected with multiple disciplines, such as Physics and Solid State Chemistry, Materials Science and Engineering. A good example of it is an infrared thermometer because it combines both optical and electrical behaviour. The thermopile is the most important part of this kind of devices. It absorbs the infrared radiation emitted by an object which depends on its temperature. Then, it converts the heat radiation into a voltage output (electrical energy). Finally, the temperature is shown in a display.

The main purpose of this work is to help students to understand the work mechanism of a thermopile on the basis of its material composition. In order to do that, an IR thermometer is disassembled and the different parts of the thermopile are studied. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) techniques are introduced to the students as the main techniques to study the microstructure and composition of them. With these experiments, students have gained knowledge about alloys and semiconductors materials and got a more accurate understanding of their role in these devices.

This experience has allowed them to keep in contact during the whole study with three main concepts of Materials Science: composition, structure and properties. This fact makes the work interesting for undergraduate students and also for teachers of Inorganic Chemistry and Materials Science owing to its pedagogical character employing a Problem-Based Learning (PBL).

Keywords:

Materials Science, IR thermometer, thermopile, semiconductor, alloys, Problem-Based Learning.