This graduation report describes the process of my graduation project. This project is the final project of the master Integrated Product Design, faculty of Industrial Design Engineering, Delft University of Technology (NL). In this particular project, we aim to explore the potential of luminous materials in the context of preventive care, in particular ‘relaxation’. We have chosen to develop a relaxation device that makes use of the visual properties of luminous materials. This relaxation device is developed for a specific market: office workers. The office is a stressful environment. Stress can cause illness, burnout and even heart disease. Next to the negative effect on someone’s wellbeing, office workers are less productive when stressed. Increasing the well-being of office workers will result in an increase in productivity and a will reduce health problems caused by stress. There are already stress-relief products and services (e.g. pause software) on the market specifically for office workers, but they do not always contribute to stress reduction. Pause software is meant for RSI prevention, but can be rather annoying when you are in the middle of writing an email and the pause software pops up. Therefore, there is a need for a product that contributes to stress reduction and increases well-being of the office worker. First, we have investigated what actually is ‘relaxation’. Relaxation is a mood state that has a low arousal level (one feels not active) and a high valence level (one feels pleasant). A stressed mood, on the other hand, has a high arousal level (one feels active) and a low valence level (one feels unpleasant). Therefore, the relaxation device should ‘guide’ the user from a high arousal level to a low arousal level, and from a low valence level to a high valence level. Second, we investigated the main visual property of luminous materials: light. We researched which of the visual properties play a role in the perception of feeling relaxed. We found that the main properties were color, intensity and color temperature. Also, we looked into research about dynamic light. For color it was not possible to find a specific hue that was perceived as most relaxing, since people have different preferences for certain colors and also have different connotations with color (e.g. green is usually perceived as positive and red as negative). Whether or not a certain illuminance level is perceived as pleasant is dependent of the color temperature of the light. A warm white light is perceived as pleasant at low illuminance levels, whereas cool white light is perceived as pleasant at high illuminance levels. Also, it was found that a high illuminance level (1750 lx) was perceived as more arousing than a low illuminance level (750 lx). Concluding from research, we could conclude that warm white light with a low illuminance level is perceived as most relaxing. From the research about dynamic light it could be concluded that the rhythm of dynamic light should be subtle and have slow temporal changes in order to be perceived as relaxing. Next to the property light, we also investigated luminous materials. We have made a benchmark of luminous materials and grouped them in several categories, like electrical luminous materials, radiating luminous materials, etc. For the product it was important that the light could change intensity, since we wanted to use dynamic lighting in the product. Therefore, only the category of electrical luminous materials (e.g. OLED, LEC) fulfills this requirement, since the electrical materials can change intensity by changing the electrical input. Based on the findings from literature, we have performed an experimental study. We have tested which rhythm was perceived as most relaxing by the participants. We varied the rhythm by changing the waveform, intensity, frequency and amplitude of the rhythm. From research on relaxation techniques we found two techniques that were based on the principle of lowering your breathing pace in order to relax: bio feedback and paced breathing. During the experimental study, we asked the participants to breathe along with the light. They had to breathe in when the intensity of the light became higher and breathe out again when the intensity decreased again. Based on the findings from this study, we selected the following values for the rhythm of the dynamic light of the relaxation device: waveform = sine wave; intensity = 2363 cd/m2; amplitude = 1700 cd/m2; frequency = 0.14 Hz. Also, we have tested two diffuse sheets of which one had a matte surface finish and the other sheet had a glossy surface finish, to investigate which glossiness is perceived as most relaxing. It can be concluded that there was no difference in perception between both sheets when the dynamic light was shown. However, the participants perceived the matte sheet as more relaxing, calming, satisfying, comforting and pleasant than the glossy sheet, when the dynamic lighting was off. Therefore, the product will have a matte finish. Fourth, we analysed the context of working at the office and we explored future trends. One of the main findings was that, in the future, people would not necessarily work at the office, but also on the go or at home. Therefore, the product needs to be compact and wireless, so it can be used on the go. Based on the findings from the analysis, a program of requirements was made for the product. The program of requirements, together with a trend analysis and the design vision, were used for idea generation. Out of the idea generation, three concepts were formed, of which one concept has been selected to develop further. The final concept is called Flo. Flo is a portable relaxation device and looks like a light bulb. The dynamic light in the product flows from one side to the other and increases and decreases in intensity, respectively. By breathing along with the light, the user is guided to a lower breathing pace and is feeling more relaxed. The product can be controlled by a squeeze interaction. The battery of Flo can be charged by USB-cable.