SMMURFS Stress Management Module Using Resistive Force Sensors

Transcription

1 SMMURFS Stress Management Module Using Resistive Force Sensors Design Team Joan De La Cruz, Gidley Dorlus Kara Hoehe, Erik Must, Philippe Saintil Design Advisors Constantinos Mavroidis, Ph.D., Richard Ranky, Ph.D. Alexandra Carver, Daniel Landers Abstract Many Americans today suffer from stress and are unable to manage their stress levels. High levels of stress have negative effects on personal health and can decrease productivity and increase medical costs. Stress balls can relieve stress by distracting the user, provide mini workouts, boost the user s mood, help the user meditate, and open up communication inside the nervous system thus releasing endorphins that help to relieve stress. However, stress management devices tend to be unsightly, cumbersome, or do not give realtime, interactive feedback to the user. To address this problem, the capstone team designed and developed a portable, instrumented stress reliever. The device needed to be attractive, customizable to the user, lightweight, cost effective, and able to provide feedback to the user. Additive manufacturing and molding techniques were used to create an ergonomic shape with an efficient fabrication process. Force sensors interact with a microcontroller and RGB LEDs to create a colorful glow to help ease stress. The soft compressible exterior of the device utilizes the progressive muscle relaxation technique to provide additional stress relief. To provide additional feedback for the user, a computer program is currently being developed to provide the user with more detailed information about their usage of the device in real time. This innovative design of the device also lend itself towards additional applications such as hand rehabilitation, hand strengthening, and improved circulation. Flexiforce Sensor Rigid Electronics Core LED Force Concentration Rod Figure 1: Final Design Soft, Compressible Outer Casing For more information, please contact mavro@coe.neu.edu

2 The Need for Project To create an instrumented stress reliever that will help manage stress. According to the American Psychological Association, stress levels for Americans are continuing to drop but they still remain high and exceed what Americans consider to be healthy. The 2011 Stress in America survey stated that 22% of Americans reported extreme stress and the impact of this stress is negatively affecting physical health. Also, when stress occurs, and the person is experiencing symptoms, only 20% of people say they are doing an excellent or very good job at managing or reducing their stress (Ref.1). Looking at the data it is clear that initiatives need to be made to manage stress. The large market for stress toys, such as stress balls, indicates that the need for stress management tools is known but that the device development is still lacking. Therefore, the objective is to create an instrumented stress reliever that will assist in stress management by being interactive with the user, aesthetically pleasing, and will be customizable to the user s needs, anatomy, and style. It has been shown that stress balls successfully distract the user, provide a mini workout, help the user meditate, and open up communication inside your nervous system, thus relieving stress (Ref.3). The Design Project Objectives and Requirements Develop an instrumented stress relieving device that is customized to the user using additive manufacturing and molding techniques. The device is designed to assist in stress management via an interactive interface and realtime feedback to the user. Design Objectives The project seeks to combine the proven technique of progressive muscle relaxation (PMR) with simple yet effective technology to produce a device that can have greater functionality than what is currently on the market. The device is intended to be sold as an off the shelf product and strives to attract as many potential users as possible, with customizability as the main advantage. The common stress ball is a great product that is very user friendly, but does not offer additional functionality to aid the user. There is currently no existing device that combines a user friendly and interactive design, with advanced technology and sensors to aid in the management of stress. Other products may include advanced technology, but are extremely complex and cumbersome to use and fail to provide the user with reliable and worthwhile feedback. The goal is to bridge this gap and build on the basic premise of the common stress

3 ball to develop a truly unique device that will assist users in managing their stress. Design Requirements The design requirements for the device were formulated based on the feedback received from interviewing various experts within the department of psychology at Northeastern University. These experts have experience using a number of different medical devices that track user data and provide feedback. Their statements allowed the team to rank the most important design requirements for a successful product. The highest ranked design requirements are; measure and monitor stress level, ergonomic and aesthetically pleasing design, real time feedback and a user interface that can interact with the consumer. Design Concepts Considered Developed a total of five Several preliminary concepts were generated and considered for preliminary concepts. Each final design selection. An early focus for design was to create a concept was designed with the wearable device, where the device would sense that the user is stressed, goal of assisting in stress and then provide stress relief. The first concept was the progressive management. muscle relaxation (PMR) watch shown in Figure 2. This is to be worn around the wrist as a typical watch. However, it uses a heart rate sensor to detect stress. The inner cuff inflates to gently squeeze the user s wrist to utilize PMR as a stress relief technique. Another one of our preliminary concepts was the Stress Relief Chest Band. This device would be worn under the clothes and around the chest of the user to detect the users breathing rate. It would Figure 2: PMR Watch determine if the user is stressed based on the breathing rate, and give a relaxing massage to the user with three pulse emitters along the back strap. The instrumented stress ball, shown in Figure 3, was the only concept generated that is not meant to be worn. It is a hand held device similar to a stress ball that uses embedded force sensors to measure how much force is being applied. Integrated LED lights change color as the force varies. The combination of squeezing the ball and watching the LED s change color reduces the users stress level. Figure 3: Instrumented Stress Ball

4 Recommended Design Concept A stress reliever with a soft, The concept we chose to pursue and complete was the transparent silicone outer layer instrumented stress ball concept. This concept was selected using a and a hard inner core. The selection matrix. The design specifications were grouped together by hard inner core houses force category and each section was assigned a weight based on the customer sensors and LED lights that needs. Each concept was scored and ultimately the instrumented stress change color based on the ball was determined to be the best concept for this particular set of force of the user s grip. design specifications (Rep. 4.7). The final design consists of two main components: a soft silicone outer layer, and a hard inner core that will house all the electronics. Outer Casing The outer casing is made of a soft and transparent silicone to give the soft feel of a stress ball and to enable LED lights to illuminate through the device. The silicone houses force concentration rods. These rods create a concentrated force on the FlexiForce sensors to ensure an accurate measurement. An additive manufactured mold cast was used to mold the outer casing with silicone rubber. The casing can be seen in Figure 4. Figure 4: Outer Casing Figure 5: Electronics Cylinder Electronics Cylinder The Electronics Cylinder is a hard inner core that houses all the electronics involved. The surface of the inner core, which is in flush contact with the inner surface of the outer silicone layer, is where the FlexiForce sensors and LED lights sit. The force sensors and LED lights are wired to the rest of the electronics housed inside, which include an Arduino Pro Mini microcontroller, Bluetooth module, and required circuitry. The electronics cylinder was made using additive manufacturing and is shown in Figure 5. Finite Element Analysis (FEA) has been performed on the electronics cylinder (Rep ). A direct force of 100 lbs, which is the maximum force a male can apply, was applied to force sensor locations to make sure it would not buckle. Material testing was also performed to understand the force transmission through the silicone. It was confirmed that the force can be accurately measured through different thicknesses of silicone (Rep 8.1.1). The functionality of this design is what will make it an effective stress reliever. When force is applied to the device the color of the LED lights will change as the force changes. When minimal force is applied,

5 the device will glow blue, and at maximum force, red, with all the colors of the spectrum in between. The Bluetooth module will make connection to a computer program or Smartphone application possible, where device usage will be tracked and viewed. All the features of this device will provide an effective and unique method of stress relief by distracting and calming the user. Financial Issues The cost of the project up to date is $445. This price will decrease as we improve upon the cost of materials and finely tune the production process. In order to determine an acceptable price for our device other products in the area of stress management were researched. Most devices cost under $100. Therefore, that was the cap we aimed to have for our device. To date, we have spent $445 building the first prototype, but this price will significantly decrease as we improve upon the cost of materials. Knowing the specific processes of making the device and mass producing the product will drive the actual cost down. The team feels confident that the final device will be able to be sold for under $100, as anticipated. Also, since only 29% of people say they are doing an excellent or very good job managing or reducing their stress, and the global sensor industry is estimated to be worth $91.5 billion in 2016, there is market potential for an instrumented and interactive stress reliever. Recommended Improvements Future improvements include testing more materials for the outer casing and developing various software applications to reach a broader audience. In the next phase of the project different materials will be tested for the outer casing and various software applications will be developed to reach a broader audience. The outer casing is currently made of a silicone rubber with a Shore hardness of 10A. However, since the mold process is easily replicated, different materials will be tested with varying degrees of stiffness. Numerous options of materials will allow the device to be more customizable to the user. Furthermore, new Bluetooth applications will be created to provide more detailed feedback. Also, some of the applications will be geared towards new audiences such as users looking to use the device for hand rehabilitation, hand strengthening, and even blood donation.