This paper presents a user-centered methodology to co-design and co-evaluate wearables that has been developed following a research-through design methodology. It has been based on the principles of human-computer interaction and on an empirical case entitled "Design and Development of a Low-Cost Wearable Glove to Track Forces Exerted by Workers in Car Assembly Lines" published in Sensors. Insights from both studies have been used to develop the wearable co-design domino presented in this study. The methodology consists of different design stages composed of an ideation stage, digital service development and test stages, hardware development and test stage, and a final test stage. The main conclusions state that it is necessary to maintain a close relationship between human factors and technical factors when designing wearable. Additionally, through the several studies, it has been concluded that there is need of different field experts that should co-design and co-evaluate wearable iteratively and involving users from the beginning of the process.

Wearable electronics make it possible to monitor human activity and behavior. Most of these devices have not taken into account human factors and they have instead focused on technological issues. This fact could not only affect human¿computer interaction and user experience but also the devices¿ use cycle. Firstly, this paper presents a classification of wearable design requirements that have been carried out by combining a quantitative and a qualitative methodology. Secondly, we present some evaluation procedures based on design methodologies and human¿computer interaction measurement tools. Thus, this contribution aims to provide a roadmap for wearable designers and researchers in order to help them to find more efficient processes by providing a classification of the design requirements and evaluation tools. These resources represent time and resource-saving contributions. Therefore designers and researchers do not have to review the literature. It will no be necessary to carry out exploratory studies for the purposes of identifying requirements or evaluation tools either.

Additive Manufacturing devices or 3D printers allow the possibility of creating almost anything. One of the most promising fields of application are wearable devices, which can be directly printed on textiles. This paper aims to study adhesion forces and warping effects when depositing a polymer onto a textile with a low-cost extrusion 3D printer. To achieve this, two different polymers (PLA and Filaflex) and six of the most common textile materials were selected. L-shaped specimens were printed by combining the two polymers and the six textiles. Most of the common printing settings were fixed for both materials, while the layer quality was 0.1 mm and 0.2 mm. Once printed, they were inspected with a Coordinate Measuring Machine and the deformation of each specimen was quantified by calculating their maximum and minimum displacements. Afterwards, each specimen was axially tested to evaluate the adhesion forces between the polymer and the textile. In terms of warping, flexible filament showed the lowest values independent of printing quality (0.56 mm and 0.3 mm) relative to the rigid filament (0.73 mm and 0.8 mm). In terms of adhesion, the combination of a porous textile and a flexible filament got the highest values, regardless of the layer height selected. The conclusion of this study is that polymer textile deposition can be a real manufacturing strategy that should be considered when thinking about the design of a wearable device to be worn on the body.

Wearables are gaining widespread use and technologies are making it possible to monitor human physical activity and behaviour as part of connected infrastructures. Many companies see wearables as an opportunity to enhance worker safety since they can monitor their workers' activity in real life scenarios. One of the goals of this technology is to integrate existing electronic components, such as sensors or conductors, in order to create fully wearable systems. This integration is constrained not only by technical factors but also by user requirements and internal company standards. This paper considers such constraints and presents preliminary research for the design of a wearable glove as a new tool to track forces exerted by workers in car assembly lines. The objective of the glove is to measure forces and compare these to maximum forces already identified by the company. Thus, the main objectives are to: (1) integrate the components based on the requirements of the users and the context of application, and (2) provide a new tool that can be used in situ to track workers. This study was carried out in close collaboration with Volkswagen through a human-centred iterative design process. Thus, this paper presents the development of a wearable device glove based on a specific design methodology where both the human and technological aspects are considered.