Sergio A. Puigcerver Palau; Juan Carlos González García; Giuseppe Caprara; Eduardo Parrilla Bernabé; Francisco Parra González; José Navarro García; Gloria Gargallo Tatay; Patricia Casado Aparicio; Clara Solves Camallonga; Mercedes Sanchís Almenara; Carlos Soler Gracia

Instituto de Biomecánica (IBV)
Universitat Politècnica de València
Camino de Vera s/n. Edificio 9C
46022 Valencia, España

Instituto de Biomecánica (IBV) has collaborated with “Calzamedi” -a company in Alicante specialized in therapeutic footwear- to create "InstantShoe", an innovative service for women’s footwear customisation at retail shops. The process consists of the in-store registration of the 3D geometry of the customer’s foot using a low-cost scanner developed by the IBV. Based on the dimensions of the foot, a specific fitting device customises the footwear manufactured using a patented upper material with “shape memory” properties. These properties allow the shoes to return to their original shape when heated, should the client decide not to purchase them in the end."

 

INTRODUCTION

Podiatric alterations are an important social problem, and it is the female population that is most affected. A "hallux valgus" (commonly referred to as a bunion) is the most frequent deformation of the foot, affecting one in every five adult women.

This and other deformations of the foot may be caused or aggravated by the continuous use of footwear that is inappropriate due to a poor fit between the foot and the footwear.

Due to trends imposed on female footwear by aesthetics and fashion, it is necessary to provide a precise fit that avoids excessive pressure and ensures comfort. However, the large differences in foot dimensions, even among people of the same size, make it very difficult to ensure that each customer buying a pair of off-the-shelf shoes ends up with a suitable fit, especially in the case of women. As a result, their footwear can be uncomfortable, and even unhealthy..

Within this context, the European Commission has funded a project known as “DemoShopInstantShoe”, the result of which has been the development of a new in-store footwear customisation service for women called "InstantShoe" (Figure 1). The technology that has been developed makes it possible to scan customers’ feet in the actual shoe shop, in order to register their 3D shape thanks to a low-cost scanner developed by the IBV. Then, depending on the geometry of the feet, an automatic fitting system deforms the footwear (manufactured from a special composite material with "shape memory" properties). The "shape memory" properties allow the footwear to adapt to the anatomy of the customer and to return to their original shape after being reheated, should the customer finally decide not to purchase them after the customisation process.

Figure 1. Logo of the InstantShoe footwear customisation service for women.

Footwear customisation process

The customisation process is done entirely at the retail shop, as described below:

ADVANTAGES

The most outstanding benefits of this innovative service are:

For consumers:

♦ A custom fit based on individual feet measurements.

♦ An increase in shoe comfort, especially for consumers with feet problems or deformations.

♦ In-store customisation, which allows the user to try the product and to buy it there and then, thereby avoiding having to wait for a long time for the shoes to be manufactured.

♦ The possibility of changing their minds after customisation should they decide not to purchase the customised shoes.

♦ Comfort and performance that are comparable to made-to-measure footwear, at a much lower price.

For shops:

♦ A major reduction in time and cost compared to the manufacture of traditional made-to-measure footwear.

♦ The technology does not limit the design options; rather it makes it possible to have varied and attractive collections.

♦ Reduced in-store shoe stocks, as there is no need for shoes of different widths.

♦  Possibility of recuperating the shoes that have been adjusted to fit, thereby avoiding additional costs related to inaccurate footwear customisation or unsold products.

FOOTWEAR WITH "SHAPE-MEMORY"

The key to this footwear customisation service lies in a novel upper material whose "shape memory” properties provide optimal fitting to the dimensions of the foot. The footwear may be returned to its original form by heating it, maintaining its initial properties. The upper material is a composite material that includes filaments of Nitinol (a commercial alloy that possesses “shape memory properties") integrated into a patented fabric (Figure 2) that is fitted between the lining and the leather of the footwear.

Figure 2. Initial and deformed state of the PCT patented fabric that includes Nitinol filaments (a commercial alloy with "shape memory" properties).

During the process to optimise the composite material, a multitude of tests have been carried out (Figure 3) to study the influence of different design parameters such as, for example, the diameter of the Nitinol filaments, their separation within the fabric, different geometric configurations of the fabric, or the type of adhesive between the fabric, the lining and the leather. 

Figure 3. Text used during the process to optimise fabric with "shape memory” properties. 

On the other hand, we have industrialised the manufacturing process of the footwear that includes the new materials. The thermo-mechanical tests that we carried out have shown that the footwear functions properly, even after more than ten customisations, without their initial properties being altered in any way (Figure 4).

Figure 4. Examples of adapted shoes.

LOW-COST FOOT SCANNER

To collect the 3D geometry of customers’ feet, the IBV has developed a foot scanner that is based on optical technology and that does not include any moving parts, thereby reducing the cost of the system and its maintenance. In addition, the scanner is small, lightweight, easily transportable, and very intuitive to use (Figure 5).

Figure 5. The IBV foot scanner.

Finally, the accuracy of the equipment was determined thereby confirming that the foot scanner possesses appropriate precision for the InstantShoe footwear customisation service (Figure 6).

Figure 6. The equipment error is of 0.82 mm (50th percentile). The areas with the greatest precision correspond to the most important regions of the foot.