## 4 Conclusions  
In the paper, a full process of development of a sensorised, specialized, low-cost customized prosthesis for an adult patient was presented. A customized design, for long-term use, was achieved, and the prosthesis was also converted into a mechatronic device, enabling to read sensor signals and monitor its use, albeit not yet in real time. Such designs are not common in the available literature. The authors realized it by a direct demand from the patients as all-purpose prostheses for adult patients with transhumeral upper limb amputations (or birth defects) are not well suited for sports activities, especially advanced cycling. After realizing a standard, modular design approach and extensive testing, the patient's feedback was further incorporated, to create a fully customized, but still low-cost device that allows him to undertake more advanced activities. The prosthesis (in its mechanical version, stripped of electronics) was fully accepted for use and the patient is currently using it for regular cycling activities. It is very difficult to compare our approach with existing solutions, as nothing similar (in terms of customization level, low cost, and induced accessibility) is commercially available. However, in patient's own words, no producer was able to support him with a prosthesis of this capability during  
Figure 34: Data registered in dynamic test (test drive). more than 40 years of his lifetime. That suggests the high level of acceptance, confirmed by another ongoing studies on a larger group of child and adult patients (some results are partially mentioned in [21]). Results of these studies will be the topic of numerous future publications). The presented sensorised device must, however, still be considered a prototype that needs further refining and improvement. Electronic components need to be hidden inside the prosthesis and protected from the atmospheric conditions. A suitable location must be found for the battery pack (so far it was carried by the patient in his pocket). The sensors arrangement must be also thought of more carefully--possibly the force sensor could be moved to the wrist-forearm joint, or another sensor could be added, to gather force data from various directions. In the software part, live streaming and visualization of results could be obtained by adding a Bluetooth or Wi-Fi module and connecting the prosthesis with a dedicated mobile application, e.g., to feed data back to the patient in time to avoid possible accidents or excessive wear of the prosthesis. All these improvements are considered and will be pursued in further iterations of the device. In terms of accessibility and easiness of production, the concept of low-cost sensor-equipped prosthesis was successfully confirmed. Very simple and accessible electronic components were used, and they fulfilled their role. Time of assembly and programming did not exceed one working day. The longest (and most costly) part of the process is 3D printing of the parts, that took a total of 54 h. It could be performed in a considerably shorter time by using parallel manufacturing with several machines; however, single large parts such as the socket still take more than 20 h to produce, and that time would be difficult to reduce significantly. It is safe to assume that after automating the design (as performed by authors in the previous research cases), it would be possible to deliver working prostheses in one week, which is still a very short time when compared to commercial personalized specialized prosthetics. It can be assumed, basing on patient's positive feedback and authors' experiences to date, that the personalized design of low-cost 3D printed prosthesis with sensors could be an invention that could change approach to amateur sports (especially cycling) by disabled people lacking one of their upper limbs, especially when they are also missing the elbow joint.