Abstract Taking advantage of the physical nature of the pyroelectric materials, in this investigation a characteristic of these materials known as the pyroelectric effect was studied and corroborated, which allows this type of materials are sensitive to infrared electromagnetic radiation, and whose response can be seen in the form of electric potential difference. In this way, in this document the theoretical basis of operation of this effect is presented, and in turn, the results of experiments carried out in laboratories of the University of Santo Tomás Bogotá D.C. The experiments were performed using the “PIR325” sensor, which is composed of two thin films of pyroelectric material. In the first instance, the response of the sensor to thermal electromagnetic radiation produced by the human body is obtained, in the second instance, the same experiment is repeated, However, on this occasion, a Fresnel lens is used to ensure the highest infrared electromagnetic energy collection. Finally, the capture of the signals obtained in each experiment is performed and the results are contrasted, where the theoretical basis of the pyroelectric effect is demonstrated, and in turn, the importance of using a Fresnel lens in applications to carry out this type of sensors.