# A Novel Earwax Self-Sampling Device: A Feasibility Study
## 4 Discussion
Thus, it might be possible that some amount of earwax was dissolved in the water syringed by the clinical method. Even though no water content is found in the earwax secretion [24], [PERSON] et al. (2013) showed that distilled water solutions have some properties for dissolving earwax [25]. Oil solubility--the main earwax component (50%) [24]--in water is larger when distilled water is used than the solubility when saltwater solution with 44 g L\({}^{-1}\) of NaCl is used [26]. This is explained by the reduced density of distilled water in comparison to salt water. However, the tap water injected by the clinical method of this study contained high concentrations of many salts. Apart from NaCl, drinking water has large concentrations of Na\({}_{2}\)SO\({}_{4}\), CaSO\({}_{4}\), KCl and CaCl\({}_{2}\) in Chile [27]. Furthermore, oil solubility in water is observed when water is warmed at 25 \({}^{\circ}\)C or above, conversely to 4 \({}^{\circ}\)C that we stored our samples. These results make it extremely unlikely that the vast earwax weight difference between both methods had been explained by some potential earwax solubility in the water injected by the medical device. More importantly, the amount of earwax is not an important variable when the main aim of this novel device is to constitute a reliable method for self-sampling earwax from healthy ears, rather than an effective device for extracting impacted earwax from diseased ears. Other variables need to be considered for assessing whether or not this novel device meets this requirement. Concerning this, the earwax weight variability (relative distance to the mean) was similar between the clinical and self-extraction method (Inter-Reliability) (\(p\) = 0.20) (Figure 3b). This result indicates that the novel device is indeed a consistent method for sampling earwax, since the comparator or reference device, also showed to be consistent in sampling earwax from healthy ears, when the VRSDs from both baseline samples that were obtained using the same clinical method (Intra-Reliability) were compared between them (\(p\) = 0.85) (Figure 3a). It might be also possible that the novel device is even more reliable than the clinical device at sampling larger volume of this oily secretion since the \(p\)-value observed when both follow-up VRSDs were compared between them (\(p\) = 0.20) (Figure 1b) was much smaller than the \(p\)-value obtained from the comparison between both baseline VRSDs (\(p\) = 0.85) (Figure 3a). This might be explained because the clinical method did not uniformly perform at sampling large volume of earwax that do not constitute a pathologic condition, such as impacted earwax. The \(p\)-value obtained was much smaller when the clinical device was also used for sampling a greater volume of earwax (\(p\) = 0.15) (Figure 3c) than the \(p\)-value obtained when the novel device was used for obtaining a larger volume of this specimen (\(p\) = 0.51) (Figure 3d). These results might imply that the novel device could also perform well at sampling earwax specimens with less weight, considering its less data dispersion. Nonetheless, all these \(p\)-values are still not significant. Therefore, future larger studies should investigate the novel device reliability at sampling earwax from both ear sides, as part of a baseline visit. An effective earwax self-sampling device may also allow the measurement of a variety of substances, such as glucose levels over different periods. A reliable and effective earwax self-sampling device is therefore needed because current self-sampling products or devices have shown no or minimal effect at removing earwax. Although we did not carry out a cost-analysis, the self-sampling device might be very likely more economical to potentially extract endogenous potential biological markers, than sophisticated technologies. For example the Realtime Continuous Glucose Monitoring (RT-CGM) device currently used to measure chronic glucose levels. Moreover, it could be utilised by patients themselves since it was well-tolerated by our participants.