## 2 Influence of Sensor Intrusion on Vocal Fold Contact Pressure Accuracy
### Results
#### 2.3.2 Mitigating Sensor Intrusion Using a Wall-Mounted, Embedded Approach  
To address the aforementioned challenges, an approach to ensure one-to-one agreement between the pressure recorded by the Millar Mikro-Cath(tm) transducer and the ground truth pressure obtained from the force transducer was developed, whereby the pressure transducer is placed in a groove machined in the aluminum plate (see Figure 3) with the surface of the sensing element oriented  
Figure 4: Variation of the pressure at the center of the contacting silicone disk as a function of offset height between the surface of the sensing element on the pressure transducer, and the surrounding contact surface of the aluminum plate (see Figure 2) for (**a**) a modulus of elasticity of \(E=0.6\,\)kPa for the contacting silicone disk, and (**b**) a modulus of elasticity of \(E=6.5\,\)kPa for the contacting silicone disk. In both plots, the line of one-to-one correspondence between the measured and ground truth pressure is denoted by the heavy, dashed, straight line. The symbols denote the mean value and the bars indicate the maximum and minimum values for each trial. Figure 5: Variation of the pressure at the center of the contacting silicone disk as a function of the modulus of elasticity of the disk, for an offset distance of \(H=0.25\,\)mm (see Figure 2). The line of one-to-one correspondence between the measured and ground truth pressure is denoted by the heavy, dashed, straight line. The symbols denote the mean value and the bars indicate the maximum and minimum values for each trial. upwards towards the contacting surface. The groove is then filled with Smooth-On(r) Dragon Skin 10 (DS) silicone and while it is still liquid the excess material is wiped from the surface of the aluminum plate with a razor blade to ensure the top surface of the silicone is perfectly flush with the surrounding plate. The silicone is then allowed to cure. This approach ensures a perfectly flat surface for contact, which avoids measurement artifacts due to physical interference caused by the sensor. Encapsulating the sensor in silicone does, however, allow the transmittal of the pressure applied at the surface of contact onto the sensing element. Due to the manner in which the silicone disk was loaded during testing, it was found that the pressure measured by the transducer varied based on whether it was at the center, or edge of the disk (i.e., the applied force was not uniform over the entire area of the disk). This variation influenced the computation of the ground truth pressure, which was computed as the output from the force transducer divided by the area of contact, which assumes a uniform pressure distribution under the contacting disk. To account for the non-uniform pressure distribution under the disk, the contact pressure was measured at 5 radial positions extending from the centerpoint to the edge of the disk. The radial position was normalized by the radius of the silicone disk, and the pressure was normalized by the pressure at the center. For each case, the distribution of the pressure was then plotted and a 3 rd-order polynomial was fit to the data points, The polynomial fit was performed to enable easy computation of the spatially-averaged contact pressure (\(p_{\mathrm{m,avg}}\)) by integrating over the area of the silicone disk. This pressure was then compared with the ground-truth pressure values computed with the force sensor. An exemplary plot of the nondimensionalized pressure as a function of nondimensional radial position for a silicone disk with an elastic modulus of \(E=1.1\,\mathrm{kPa}\) is shown in Figure 6, where the overlaid polynomial fit is expressed as \(p(r)/p_{\mathrm{cent}}=0.6438(r/R_{\mathrm{o}})^{3}-0.9412(r/R_{\mathrm{o}})^{ 2}+0.04751(r/R_{\mathrm{o}})+1.0\), where \(r\) is the radial position measured from the center of the disk, and \(R_{\mathrm{o}}\) is the outer radius of the silicone disk. For all investigated elastic moduli, the \(R^{2}\) value of the polynomial fit was \(>0.996\).