## 3 Experiments and Results
### Guideline for Fabricating Pressure Sensors for Individual Applications  
This study examines the pressure measurement characteristics of the Velostat film sensor according to the fabrication size and presents the fabrication guidelines for the sensors, which can be applied individually depending on the user and the attachment points. Figure 7a shows eight sensors fabricated by increasing the length by 10 mm to check the pressure change pattern according to the size of the Velostat film. Figure 7b shows the experimental state when pressure is applied to the sensor using a force gauge. The fabrication sensor was sequentially pressurized below the average pressure range of 200 kPa inside the socket [36; 37; 38]. Figure 8 shows the range of pressure changes shown by the pressure application and its aspect. A suitable pressure range for the internal application of the sensor is one in which it does not cause saturation and exhibits linear properties. Therefore, in this stage, the  
Figure 5: Prediction of the pressure change according to six lower limb movements: Standing, Walking, Up Stair, Down Stair, Stand to Sit, Sit to Stand. Figure 6: Detection flowchart of the control method change intention. range with linear characteristics was identified before saturation occurred, and this is shown in Table 2. With the fabrication of the sensor with reference to the pressure range selection guidelines presented in Table 2, it will be possible to apply the sensor considering individual pressure ranges. The shape of the fabrication sensor proposed in this study is rectangular, but various types of sensors, such as circular, elliptical, and diamond-shaped sensors, can also be fabricated depending on the internal structure of the socket. This section aims to identify the unfastened state that occurs when 2500 mm\({}^{2}\)-sized sensors are attached to four flexion surfaces in order to present an individual sensor cutting method according to the socket flexion. Figure 9 shows the experimental results of determining the unfastened state according to the flexion radius and the amount of cutting of the outer part. Data at the top of the graph are the initial output values identified by attaching sensors to four flexion surfaces with different flexion radii. The unfastened state of each sensor can be confirmed through the initial output value of the sensor. The initial output value when the pressure is not applied is 500 mV, set thro \begin{table}
\begin{tabular}{c c c} \hline \hline
**Range** & **Sensor Size** & **Considerations for Application** \\
**[kPa]** & **[mm\({}^{2}\)]** & **Convertions for Application** \\ \hline Under 50 & 400, 600 & Narrow area and pressure range allow for large changes in small pressure. \\  & & Suitable for use in areas with small muscle mass or for children and low-weight users. \\ \hline Under 100 & 800 & Suitable for applications to areas with pressure generation of 100 kPa or less to users. \\ \hline Under 150 & \
\begin{tabular}{c} 900, 1000, \\ 1200, 1600 \\ \end{tabular} & Suitable for applications to areas with pressure generation of 150 kPa or less to users. \\ \hline Under 180 & 2500 &
\begin{tabular}{c} Large area and pressure range: Suitable for use in areas that require a detailed check \\ of muscle movement or in users with high weight and high activity. \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Size of the Velostat-film-based sensor is suitable for application depending on the pressure range inside the socket. Figure 8: Pressure measurement ranges according to the size of the Velostat-film-based sensor. Figure 7: Fabrication of a sensor group and pressure application experiment to verify pressure change characteristics according to size: (**a**) sensor comparison group to verify pressure measurement ranges according to size; (**b**) pressure application experiment. resistance. Therefore, if a measurement value exceeding 500 mV is verified, the bending or crumpling of the sensor occurs due to the unfastened state.