# Applications of Capacitive Imaging in Human Skin Texture and Hair Analysis
## 4 Discussion  
In this study, we achieved to summarize the importance of skin and hair analysis in a variety of scientific fields, we introduced and analyzed the apparatus of capacitive imaging systems using a Maxwell-based simulation, we suggested algorithms for information extraction using such equipment and we conducted experiments to evaluate the overall system performance. Figure 8: Video snapshots from water desorption in hair samples. The first row shows five frames from hair capacitive images over time after acclimatization in 67%RH. Rows two and three show the same sample after acclimatization in 75% and 85%RH chambers correspondingly. The contrast is modified to highlight hair samples. Figure 9: Hair water content desorption curves using samples from three volunteers and for three different humidity acclimatization chambers. The simulation compared the penetration depth of the electric field between Corneometer C825 and Epsilon E100. The results show that both instruments have satisfactory penetration depth for skin measurements, with CM825 reaching twice the measurement depth. This implies that if stratum corneum thickness is less than 40 \(\upmu\)m, errors should be found in a side-by-side comparative study. Such results have not been found in the literature and might be of interest to achieve in future work for validation of our simulation. Another conclusion we draw by this simulation is that both instruments have insufficient measurement depth for hair analysis. Their electric field reaches the shaft cortex and it will give some reasonable readouts, but it could not represent the absolute hair water content. Our experiments focused on the evaluation of capacitive imaging systems in cosmetic and skin research studies. The first experiment demonstrated how capacitive images can be used to extract skin texture information. While this could be performed with any calibrated spectroscopic, expanding applications of existing laboratory equipment is one of our goals. The suggested algorithm successfully detected the skin polygons and measured their average surface area. The results associate well with subjects' age, giving \(-0.71\) correlation with <0.0006 statistical significance. Furthermore, the achieved correlation value agrees with [10; 11], where the correlation between age and polygons density were calculated to \(-0.64\) and \(-0.65\) in the dorsal hand and solar forearm correspondingly. The second experiment used the GLCM to estimate the length of wrinkles. In order to determine the reliability of this method, we compared our results with calibrated spectroscopy for a small group of samples. The experiment was not extended further because the need to bring the capacitive sensor in contact with the sample results to skin deformation. This is enough to twist the frame and make repositioning algorithms to fail identifying the same wrinkle. Nevertheless, the same logic could be applied on objects with greater surface area (e.g., moles or scars) and track changes in their dimensions over time. Our last experiment focused on measuring water desorption rate from scalp hair samples. The experimental results shown that the measurement apparatus is capable of differentiating desorption rates from young and elder subjects. This means that the comparative interpretation of the results between samples are in agreement with the literature [40], indicating that such systems can be used in hair analysis studies. Unfortunately, the observed desorption rates are lower than the ones reported in similar studies using different measurement methods (e.g., DVS or thermogravimetric) and for many of our samples the expected baseline was not reached. More specifically, [PERSON] et al. [40] found that it takes only 58 min for soaked hair samples to return to their baseline hydration using DVS. To conclude, we believe that capacitive imaging sensors can be used for skin texture analysis and human skin age classification. We also believe that evidence is found for capacitive imaging application on hair water loss studies.