To aid in the design of future wearable health devices (WHDs), contact pressure between the distal forearm (wrist) and two different wrist-worn devices was investigated in this work. The first device included eight force sensors arranged in series along the length of a wristband to measure the pressure profile. The band also included a tensioner device for manually tightening the band while on a wrist. Testing was done on dummy wrists and the results were statistically significant supporting the hypothesis that areas of the wrist with lower radius of curvature will experience higher contact pressures generally and a faster rate of change in pressure as the band is tightened. The second band included a controller, actuator, and force sensors for actively controlling the contact pressure of a photoplethysmography (PPG) sensor on the wrist during user motion. A total of eight tests were performed on six human subjects to estimate previously unknown design parameters related to contact pressure control of a wrist-worn device. Participants were asked to perform several actions including tapping their finger at different rates, tossing a ball, wrist flexion and extension, and making a fist. The design parameters investigated were system stiffness, range in contact pressure caused by motion, range of motion in the radial direction required to maintain a desired pressure, arterial pulse pressure amplitude and its relation to pressure tolerance, and system response time required to maintain a constant pressure. System stiffness was observed to be greater during motion (dynamic) than during rest (static) and to increase with increasing contact pressure. The change in contact pressure caused by motion was around 18 kPa in some cases and the maximum range of motion to maintain a contact pressure was about 7 mm. The arterial pulse pressure amplitude ranged between 0.05 to 0.3 kPa. It was estimated that a maximum sensor platform speed of 30 mm/s or greater is required to maintain a constant contact pressure during large motion actions such as flexing the wrist up and down. Finally, no significant differences were observed in the PPG signal between states in which the contact pressure was controlled vs. not controlled.

Every year, people are injured or even drowns in pools all over the world. Even in pools with monitoring lifeguards, accidents happen. One reason for submerge injuries or drownings is that they often are silent, which make incidents hard to detect. Lately, more reliable systems for pool surveillance have entered the market: Technology ranging from camera monitoring systems to wearables that detects if a person lying lifeless in the pool. This to, ensure good safety for bathing visitors around the world and make the work of the lifeguards easier. This master thesis project regards the development of a new wristband for a Pool Safety and Drowning Detection System. This involved studying the system, investigate the involved stakeholders, gather information about the current wristband and analyse the current situation. However, the primary focus for this master thesis project has been to create and design a; “One-size fit all” wristband, based on human measures, a more robust design, and with a higher resistance against wear. The master thesis project is done with Sentag AB as clients together with third party developers. Sentag´s system includes three sizes of wristband, sensors in the water to pick up signals, and a central unit from where the system is operated. When the alarm is triggered the wristband sends a signal in the water which the sensors pick up, and pass the information to the central unit, which notifies the lifeguards. Also, the wristbands contain a RFID tag which allows the user to use the wristband as a key card which can be used for lockers, make payments, and passing gates. Sentag aims to be a leader in high quality drowning detection technology on an international market. They want to improve their product to reach a broader market and prevent accidents. The project has followed a human-centred design process to understand the perspective of the lifeguards who operate the system, and also to better understand the users wearing the wristband. The project was performed in five phases, starting with a Project Plan and Research, followed by Context Immersion, Ideation, and Implementation. The work is based on demands form Sentag and third party consultants and findings from the Context Immersion phase where the team interviewed and observed stakeholders, analysed the system, and investigated materials. The team worked iterative within each phase, meaning the methods were repeated if necessary. In the Ideation phase the creative work was performed, and in Implementation phase were prototypes and evaluations performed to find a final solution. The project resulted in a “one-size fit all” wristband concept, which can be worn by people from three years upwards. The new design consists of several parts, most of which is a soft wristband casing, which protects the technology unit against wear and scratches. It is now possible to replace the bracelet without tools, which previously required and exposed electronics. The work presented in 3D visualizations and 3D printed prototype. / Varje år skadas eller till och med drunknar människor i pooler världen över. Även i poolområden med övervakning händer olyckor. En orsak till detta är att drunkning ofta sker helt ljudlöst, vilket gör att incidenter är mycket svåra att upptäcka. På senare tid har mer tillförlitliga system för poolövervakning kommit in på marknaden. Allt från kameraövervakningssystem och personliga larm som upptäcker om en person ligger livlös i poolen. Detta för att säkerställa en god säkerhet för besökare och göra arbetet som badvakt lättare. Detta examensarbete handlar om utveckling av ett nytt armband för ett säkerhetssystem i poolmiljöer. I arbetet studerades nuvarande poolbevakningssystem, intressenter, information om de aktuella armbanden och arbetet omfattade analysering av nuläget. Huvudfokus under detta projekt har varit att skapa och designa ett armband som passar alla och som baseras på människors kroppsmått. Det nya armbandet skulle vara mer motståndskraftig mot slitage. Detta examensarbete utförs med Sentag AB som klienter tillsammans med tredjepartsutvecklare. I Sentags system ingår tre storlekar av armband, sensorer i vattnet för att plocka upp signaler, och en central enhet där systemet styrs ifrån. När larmet utlöses sänder armbandet en signal i vattnet, som sensorerna plockar upp, sensorerna vidarebefordrar informationen till centralenheten, som meddelar badvakterna. Armbanden innehåller också en RFID-tagg som tillåter användaren att använda armbandet som ett passerkort, nyckel till skåp, göra betalningar, och passera grindar. Sentag strävar efter att vara ledande i högkvalitativa drunkningslarm på en internationell marknad. Nu vill de förbättra sin produkt för att nå en större marknad och förebygga olyckor. Projektet har följt en designprocess som är centrerad kring människan för att förstå badvakternas perspektiv som använder systemet, och även för att bättre förstå användarna som bär armbandet. Projektet genomfördes i flera faser där processen började med en projektplan och litteraturstudie, följt av informationsinsamling, Idégenerering och Implementation. Arbetet bygger på önskningar från Sentag och tredjepartskonsulter och den information som framkom under informationsinsamlingen, där gruppen intervjuade och observerade intressenter, analyserade systemet och sökte efter lämpliga material. Processen var iterativ, vilket innebär att metoder som användes inom faserna repeterades efter behov. I idégenereringsfasen skedde det kreativa arbetet och i implementeringsfasen gjordes prototyper, 3D modeller och utvärderingar för att finna en slutgiltig lösning. Projektet resulterade i ett armband med en storlek som kan bäras av alla. Det kan bäras av personer från tre år och uppåt. Den nya designen består av flera delar, varav huvuddelen är ett mjukt armbandshölje, som skyddar teknikenheten mot slitage och repor. Det är nu möjligt att byta ut armbandet utan verktyg vilket tidigare krävdes samt exponerade elektroniken. Arbetet presenterades i 3D visualiseringar och en 3D printad prototyp.

Titel: Omedveten arousal i butiksmiljön. Nyckelord: Arousal, omedveten arousal, servicescape, butiksmiljö, konsumtionsbeteende, GSR-armband, eyetracking, elektrodermal aktivitet. Syfte: Syftet med denna studie är att undersöka vilka faktorer som framkallar omedveten arousal i en riktig butiksmiljö. Vidare vill vi undersöka om skillnader i kundrelaterade konsumtionsvariabler påverkar omedveten arousal. Metod: Studien kombinerar en kvantitativ och kvalitativ ansats där 60 respondenter deltog i studien. Data samlades in via två enkäter, GSR-armband och ett par eyetracking-glasögon. Bidrag: Studien har bidragit med en kategorisering av omedvetna arousalutslag baserat på vad respondenter reagerat på i butiken. Skillnader i kundrelaterade konsumtionsvariabler har identifierats i förhållande till omedveten arousal. Originalitet: Med hjälp av studiedesignen har data kunnat samlas in i en riktig butiksmiljö. Respondenterna har således kunnat handla som vanligt i en miljö med andra kunder, personal och fysiska faktorer i butiken. / Title: Unconscious arousal in a store environment. Key words: Arousal, unconscious arousal, servicescape, store environment, consumer behavior, GSR-wristband, eye tracking, electrodermal activity. Purpose: The purpose with this study is to examine what factors evoke unconscious arousal in a real store environment. We will also examine if there are any differences in customer related consumption variables which affect unconscious arousal. Method: The study combines a quantitative and a qualitative approach where 60 respondents participated in the study. Data was collected by two surveys, a GSR-wristband and a pair of eyetracking-glasses. Contributions: The study has contributed with a categorization of unconscious arousal peaks based on what the respondents reacted to in the store. Differences in customer related consumption variables have been identified in relation to unconscious arousal. Originality: The study design has allowed data to be collected in a real store environment. The respondents have been able to shop as usual in an environment with other customers, staff and physical factors in the store.