In the past few decades, medical and biological researches gained more and more attention. The ever-growing need for such researches caused many medical applications to develop. Collecting data from a living human body is a complex task and needs circumspection. In this paper, specific issues of the most important part of such a data acquisition system is presented, the design of a low pass filter. The major issue to overcome in the design of a system that is aimed at being built into the human body is creating large value capacitances needed to the realization of filters for the specific application. After presenting the special requirements for low pass filters for medical applications the method of creating large capacitors is presented in details in the paper.