## 4 Results and Discussion  
### Sample Conductivity  
The sheet resistances of most samples under investigation are depicted in Figure 5. The samples not shown there had a sheet resistance that was too high to be measured, i.e., higher than \(1\) k\(\Omega\), which is the upper limit of the measurement instrument used in this study. The lowest sheet resistance values were reached by silver- and copper-coated woven fabrics (Figure 5a), followed by the crocheted fabric with conductive yarn. This finding can easily be explained by silver and copper having very high conductivities, with silver being the most conductive metal and copper having only around 7% lower conductivity.  
Figure 4: Signal flow graph of the whole system.  
Figure 3: (**a**) Test set with amplifier connected; (**b**) model of the system.  
Here, the more important parameters are apparently the cover factor of the metallization on the woven fabrics (i.e., the ratio of the coated area relative to the overall fabric area), which seems to be similar according to Table 1, and the conductive layer thickness, which is not given by the fabric producers. The crocheted fabric with conductive yarn contains large pores (cf. Table 1), resulting in a slightly higher sheet resistance than both metallized woven fabrics.  
The crocheted fabric with magnetic and conductive yarn shows not only a much higher sheet resistance, but also a significantly higher standard deviation (cf. error bars in Figure 5a), which can be attributed to the large open pores and the addition of non-conductive PES yarn making it difficult to reach a proper contact between the electrode pins and the conductive part of the fabric.  
Among the less conductive materials whose sheet resistances could be measured (Figure 5b), the PEDOT:PSS coating and the conductive PLA had resistances of around 100 \(\Omega\) with relatively small standard deviations, while both Powersil-coated fabrics had larger and stronger varying sheet resistance. This can be explained by the hand-coating process, which leads to thickness variations of the highly viscous coating material, which is thus hard to process with constant thickness. On the other hand, the crocheted fabric from magnetic yarn contains 80% non-conductive fibers, making contacting of the conductive parts complicated.  
The samples that could not be measured are pure and magnetic PLA, both of which are non-conductive, as well as both nanofiber mats that contain nanoparticles of the semiconductor nickel ferrite and thus cannot be expected to show a high conductivity either. Moreover, the nanoparticles are embedded inside the nanofiber mat as in a non-conductive matrix and normally do not form percolation paths, so no measurable sheet resistance could be expected, even if the nanoparticles were highly conductive. Instead, these nanofiber mats belong to the magnetic samples tested here in addition to the conductive ones due to their potential to shield static magnetic fields.  
These measurements suggest that silver- and copper-coated fabrics, as well as both crocheted fabrics with conductive yarn (with or without additional magnetic yarn), may have good EMI shielding effectiveness. The latter, however, have large pores that can be expected to reduce the \(SE\) values. Section 4.3 reports the respective measurements of the  
Figure 5: Sheet resistances of conductive samples: (**a**) samples with sheet resistances in the m\(\Omega\) range; (**b**) samples with sheet resistances in the \(\Omega\) range.  
EMI shielding effectiveness of these samples compared to the crocheted fabric with purely magnetic yarn.