## 3 Results and Discussion
### Test Results with Hybrid Paper-Based Sensors
In the first scenario, the sensor was pressed twice within one second (Figure 9a). It was followed by a two-second pause, after which the experimental procedure was repeated. In the second scenario, the sensor was acted upon in a cycle of one press every second, followed by a two-second pause (Figure 9b). In all cases, the measurement series were separated by a time interval of 10 s, during which the sensor was not touched at all. Using a sampling frequency of 1000 Hz gave satisfactory reproduction of the assumed pattern. The result indicates that advanced mechanical interaction patterns can be recorded for the presented measurement system based on a hybrid paper solution. The inspiration for this type of experiment was an attempt to imitate normal heart sounds. At this stage of the work, attempts to record the heart rate using sensors stabilized on the wrist or neck, however, did not yield some satisfactory and repeatable effects. This results from the intensity of the forcing pulse being too low compared to the noise and interferences observed in the measurement system. Figure 8: Response curve of periodical mechanical stimulation of sample #3 at a frequency of about 0.35 Hz. Signal sampling frequency 1000 Hz. An interesting effect was observed when the neodymium magnet was cycled over the sensor surface (Figure 10). A small in magnitude but measurable change in the relative resistance of the sensor in an alternating magnetic field could be observed. It may be attributed to the generation of additional electric current within the system, which is the result of the changes in the magnetic field intensity caused by the magnet's periodical movement. This effect is superimposed on the constant component, resulting from the flow of constant current underlying the operation of the test system. It is worth mentioning that other authors observed a similar effect of an external magnetic field on the properties of a sensor made of a magneto-rheological elastomer [2]. This observed phenomenon may provide a basis for the design of cost-effective and non-contact displacement sensors. In addition to typical tests showing the possible applications of the developed sensors for inanimate physical objects, additional studies were carried out that confirmed the  
Figure 10: Effect of alternating strong magnetic field on sample #3. Figure 9: Cyclic mechanical interaction with finger; sample #4: (**a**) first scenario, (**b**) second scenario. Signal sampling frequency of 1000 Hz. applicability of the hybrid paper-based sensor system for health monitoring purposes. Figure 11a illustrates using a sensor stabilized on the index finger, which was bent cyclically. A clear relationship between the recorded signal and the applied forcing can be observed. Figure 11b portrays the effect of air blown out of the mouth, perpendicular to the sensor surface, on its response. The experiment was repeated recurrently for different intensities of exhaled air. The courses presented give a reasonable indication of the activities carried out, while the correct interpretation of the signals obtained remains an open question. Figure 12 shows the signals measured with the sensor stabilized on the surface of the neck. In order to compare the effect achieved in the first stage, the signal was recorded in the absence of activity (Figure 12a). Random and chaotic signal runs are likely the result of electrical noise generated in the measurement system and mechanical disturbances characteristic of the sensor's location resulting from human activity. The following runs show the response of the system to physiological actions, such as pronouncing alphabet letters aloud (Figure 12b), swallowing (Figure 12c), and head turns (Figure 12d). Some clear correlation between the activities performed and the recorded courses can be observed, which differs significantly from the previously recorded background. Furthermore, slight differences can be found between the courses obtained for the individual activities.