## 3 Results and Discussion
### Electrical Parameter Testing and Drug Detection  
Three microfluidic chips were fabricated using each of the four conductive textile samples, and they were tested in order to demonstrate a proof of the proposed concept. The instrumental errors were eliminated by a calibration procedure, as well as by setting a medium integration time and averaging four consecutive measurements. After the fabrication of the microfluidic chip, as shown in Figure 1b, measurements of electrical resistance between the two terminals when the dry fabrics were placed into the microfluidic channel were conducted. The measurements were repeated when the artificial sweat was injected by syringe into the channel, as illustrated in Figure 1a. Afterwards, the sweat solution with CPA medication was injected into the channel on all investigated textile materials. A magnified view through the central hole of the microfluidic structure on these four fabrics is presented in Figure 4, including the case when the sweat was injected into the fabric (Figure 4g). Figure 2: SEM images of control and impregnated CO and PET fibers. These four different substrates in the middle of the microfluidic platform were exploited as a medium for delivering a small volume of artificial sweat and sweat with dissolved CPA (2 _w/v_%, 4 _w/v_%, and 6 _w/v_%). Thanks to the optical transparency of the PVC foils, it was possible to visually observe (from both sides) the process of fluid penetration into the internal structure of the studied fabrics. The fabrics in the middle of the microfluidic platform were very quickly completely soaked by the applied fluid, and the measurement of electrical characteristics was ready to begin. The electrical resistance as a function of frequency was measured for all studied fabrics and CPA concentrations. In all studied cases, the resistance of the dry structures was around 12 times higher than that of chips soaked with artificial sweat placed inside the microfluidic channel. Such behavior was expected because the ions in the artificial sweat solution enabled easier conduction between the two terminals and lower electrical resistance. Figure 5a shows the measurement results for the structure with PET-PANI/TiO\({}_{2}\)-1 fabric, which was already presented in Figure 4g. The shape of the curves in Figure 5a is completely consistent with the results for the real part of impedance from [42]. Three regions can be distinguished: (1) in the low frequency range, the polarization region; (2) in the middle frequency range, a region almost independent from frequency variation; and (3) at high frequencies, the dispersive region. This high frequency drop is related to the charging/discharging mechanism of the double-layer capacitance, which represents one of the elements in the equivalent circuit modelling. The measured resistances were relatively constant in the mid-frequency region (from \(10^{4}\) to \(10^{7}\) Hz). This could be due to the relaxation mechanism of the polymer chains [43] in the low frequency range (between \(10^{2}\) and \(10^{4}\) Hz) as well as the rearrangement of polaron and bipolaron structures of the PANI/TiO\({}_{2}\) nanocomposite at higher frequencies (above \(10^{7}\) Hz). Bearing this in mind, we selected one frequency point (100 kHz) from these regions to present the obtained results for differently impregnated substrates. These results are depicted in Figure 5b, and they were used as calibration curves in the in-house-developed electronic system. Figure 3: FTIR spectra of (**a**) CO and CO-PANI/TiO\({}_{2}\)-1 samples and (**b**) PET and PET-PANI/TiO\({}_{2}\)-1 samples. Figure 4: (**a**) SEM image of CO fabric, (**b**) SEM image of PET fabric, and magnified views of the microfluidic platforms with (**c**) CO-PANI/TiO\({}_{2}\)-1; (**d**) CO-PANI/TiO\({}_{2}\)-2; (**e**) PET-PANI/TiO\({}_{2}\)-1; (**f**) PET-PANI/TiO\({}_{2}\)-2; and (**g**) PET-PANI/TiO\({}_{2}\)-1 with injected artificial sweat.