**2.5 Material and texture**

Material selection is a key step in orthotic/prosthetic design. From the perspective of product design, material characteristics have a strong impact on the physical product. It is important to ensure the material selected has the necessary mechanical and physical properties required for the functional needs of the user. Concomitantly, careful consideration must be given when addressing more intangible characteristics like perceived values, personal associations and emotions. A study by, provides a detailed summary of key parameters to be considered by designers when selecting materials with a greater emphasis placed on the intangible characteristics of materials for improving the product design process. With advancements in material research and technology, it is possible, with new material options, to satisfy these intangible needs. Most medical prosthetic devices use metallic components to provide the necessary mechanical strength and polymers or plastics for the external encasing. Newly developed inert materials such as fiberglass, biopolymers and various metal alloys have been used to improve mechanical strength. The synchronization between user perception and product material should also be considered. Material texture preferences may be influenced by gender and various socio-cultural factors. Material, which mimics skin, may or may not be desirable depending upon the circumstances.

#### **2.6 Adaptability to fashion and clothing**

Just like physically fit human beings, people with special needs also have the desire to be perceived as attractive. An individual's appearance is highly affected by the style of clothing and fashion accessories being worn. However, the ability to use the prosthetic under fashionable clothing is an aspect often overlooked by medical practitioners when designing the device. Velcro straps can be used to affix bulky orthotic splints and braces which are often prominent, detract from personal esthetics and make it difficult to wear clothing over top. Due to bulkiness and prominent visibility of prosthetic devices, the range of clothing is limited Current design technologies have the ability to produce customized and sleek products which can be either hidden under clothes or can blend with an ensemble by matching the contour of an individual physique.

The majority of lower limb prosthetics are designed for wearing normal flatsoled footwear. This reduces the number of footwear options and may negatively alter the biomechanics of the prosthetics predisposing the user to postural imbalance and injury. Hence, there is a need for designing adjustable ankle prosthetics, which not only support body weight but can also adapt to different types of footwear. Following fashion and style trends are often important for the reasons of personal esthetic preferences. The aforementioned design considerations would help ortho-prosthetic users have greater autonomy and fewer limitations when it

#### *Design and Fabrication of Prosthetic and Orthotic Product by 3D Printing DOI: http://dx.doi.org/10.5772/intechopen.94846*

#### **Figure 4.**

*Industrial growth in worldwide by 3D printing process.*

comes to choice of clothing. This could have positive effects on social interactions psychological well-being and self-confidence.

## **2.7 Other factors**

Factors like age, gender, cultural affiliations and personal attitude affect consumer esthetic tastes.Previous studies have shown that males prefer more masculine product patterns whereas females are more inclined towards products of beautiful and elegance. Regulatory and legal factors also affect material selection as products often needs to comply with standards approved by the Food and Drug Association (FDA). Industrial Growth in worldwide by 3D printing process as shown in **Figure 4**. Other factors, which also affect the design process, include the cost of manufacturing and affordability of the target users. However, esthetics should not be compromised based on manufacturing costs or material selection. Although traditional manufacturing processes help in producing more economical medical prosthetics in mass scale, 3D printing has proven to be highly cost effective concerning the customization of products. 3D printing can also avoid f material waste incurred during the casting and manufacturing process. In 100 addition, 3D printing techniques can be used to facilitate a modular development of orthoprosthetic devices for individual customization.

### **3. Design approach – modular design**

Modular designs are based on the concept of separating products into multiple parts, segments or modules that can be individually modified and customized. Recently, a large number of research contributions have been made in this particular area. A study done in 2014 proposed a similar approach, which they termed "Non-finito" product design. The products are intentionally unfinished giving users the option to customize and complete them based on their own personal choices and creativity. This kind of approach can help in achieving mass customization and facilitate product design flexibility based on individual preferences. Allowing users to be actively involved during the design process can help to initiate a better product-user relationship, which would better address the user's needs. This can

also make the potential problems encountered in the design phase more visible to the designers. However, this type of design approach is seldom adopted in the field of medical product design. Therefore, the team attempted to incorporate the concept of a modular design approach without compromising the primary function (i.e., locomotion and movement) of the prosthetic limb. As previously discussed in the introduction, for the construction of the orthosis two important points are necessary, firstly, the scanned arm, and secondly, the anthropometric measurements. The first step to make the model in 3D, is to open the file in which the image of the scanned arm is located as shown in **Figure 5**.

Once the file is opened, the sketch of the measurements is drawn. For the sketch, three drawings are drawn, corresponding to each small size (S) measurement, which are, the perimeter of the forearm (plane 1), the perimeter of the wrist (plane 2) and the hand's breadth (plane 3)as shown in **Figure 6**. This way, the orthosis construction will be easier, since, to start from correctly adjusted measurements, a stabilizing orthosis will be achieved.

The structure has been created by surfaces, where the tool "lofted surface" has been used, and the 3 edges corresponding to the measurements have been selected. Then, the previously created surface has been thickened and part of the structure has been cut to achieve the desired esthetics. Also, the whole piece has been rounded off for a better result. Finally, a sketch has been made on the top face, where holes of random size and position are created, thanks to which better ventilation and hygiene will be possible.

**Figure 5.** *3D scanning of human hand.*

**Figure 6.** *Sectioning of 3D scanning file.*

*Design and Fabrication of Prosthetic and Orthotic Product by 3D Printing DOI: http://dx.doi.org/10.5772/intechopen.94846*

**Figure 7.** *Final 3D printed prototype for hand support.*

Last but not least, the assembly is going to be made between the three components. The orthosis structure and the velcro bands are the parts of it, so a 3D model is going to be made. As final result it has been obtained a mass of 0,125 kg (125 g) as shown in **Figure 7**. A rather small value, so it can be said that the designed orthosis is a low weight orthosis, and that therefore it has been possible to satisfy the needs of a light and comfortable orthosis for the patient.
