###### Abstract
A pressure sensor is attached to the inside of the socket and classifies the pressure change according to the movement in the form of a trigger or pattern [25]. Past pressure-sensor-based studies have mainly applied capacitive pressure sensors or resistive pressure sensors. A study using the capacitive pressure sensor fabricated a capacitive sensor in the form of a fiber or film [26]. Pressure data from the capacitive sensor according to the movement of the lower limbs could be classified into five movements, namely standing up, flat locomotion, stair climbing and descending, and ramp locomotion, based on the quadratic discriminant analysis method. However, the results of these studies reflect the method's performance only in limited experimental environments, and capacitive sensors are vulnerable to skin impedance, which changes when the temperature rises inside the socket and sweating occurs. In addition, the capacitive pressure sensor has a slow recovery characteristic, with a full recovery time of approximately two seconds after pressure application. Since the average cycle of locomotion takes approximately two seconds, a pressure change occurs due to the movement of the lower limb before the full recovery of the sensor, affecting distinct pressure change data between each movement. As mentioned, the system using a capacitive pressure sensor shows appropriate pressure change performance within a limited experimental environment, but further studies are needed to apply it as a system suitable for the internal environment of the socket. In comparison, the resistive pressure sensor is relatively strong against the noise caused by a rise in temperature and sweat generation inside the socket, and the recovery time is relatively fast [27; 28]. Therefore, it is considered that a resistance variable pressure sensor would be suitable for application inside the socket. Based on this, a related study has suggested the possibility of intuitive intention detection in the form of a trigger according to five movements by attaching an FSR (force-sensitive resistor) sensor, a film-type resistive pressure sensor, to the front and rear parts of the socket [29]. However, the FSR sensor applied in the above study was a small circular sensor with a diameter of approximately 13 mm. The small sensor could only check the pressure change in the local area when attached to the inside of the socket, making it difficult to verify the pressure change if a pressure application point occurs far from the attachment position. In the above study, the classification possibility of five lower limb movements was verified, but they were found to be influenced by the limited experimental environment in which the pressure application point and the sensor attachment position matched. The lower limb muscles in an amputated area have shorter muscle lengths and less muscle mass, as well as muscle contraction and relaxation, compared with non-amputated lower limbs. The reliability of pressure-change-based judgment data according to movement is reduced when the pressure change is checked only at a local part of the amputated lower limb since the reproducibility is reduced due to the lack of pressure change detection [21; 22]. This problem causes the occurrence of a judgment error, which leads to a malfunction in prosthetic leg control, and there is a risk of a fall accident. This must be addressed in order to discern the user's intention according to lower limb movement. In conclusion, it is necessary that the pressure sensor system applied inside the socket is not vulnerable to skin impedance and is made of a resistive variable material with fast recovery properties. In addition, it is necessary to apply it in a wide and flexible form to sensibly check the pressure change at the amputated lower limb. Therefore, this study proposes a pressure sensor system inside a prosthetic socket that can be fabricated in a wide single form and presents its fabrication guidelines.