Vibrating Knee Brace by Trish

Project Description

The intention of my final project is to build a problem-solving prototype for people who suffer from knee pains more specifically wear and tear of the joint from excessive use. As someone who has had first-hand experience with knee issues my research explored a few problems:

  • Physiotherapy which is time-consuming and expensive, with the help of this device which is intended to be an alternative (disclaimer: if recommended by a doctor) for physiotherapy for long term use as it will be a one-off purchase.
  • Running and ExerciseRunners and athletes tend to exert their bodies with the activities they do and over time they start to experience wear and tear. This device could potentially be used by people who have active lifestyles to help with knee support and rehab.
  • DrivingThere is nothing worse than having to drive when someone’s leg is in pain hence this device could potentially help ease the pain while someone is driving.
  • Discomfort ImprovementOne other way this device could be useful would be to improve the comfort of someone while they sit for long hours working, some features would include a reminder for the user if they have sat for too long in one position without stretching their knee as well as adding a pulse vibrating sensation every 30 or so minutes.

For my study, I focused my research on designing the knee brace for very mild exercise such as walking and post-workout stretches. The knee brace has four modes which are indicated by the light emitted from the NeoPixels on the circuit playground express. The brace has four DC vibration motor modules two are located on the top strap of the brace and the other two on the bottom. When the NeoPixels are red it indicates all the motors are off, yellow indicates the top motors are on, orange is for the bottom motors and green indicates all the motors are on. There is also another mode that is activated by the accelerometer feature on the playground express when someone is in motion the motors go on and off in intervals. The vibration intensity is set to a comfortable moderation so as not to cause an intensive sensation when someone is using the knee brace. To change the different modes of vibration one must press the right button on the circuit playground express.


Parts & Materials List


  1. Adafruit Circuit Playground Express (1) PART: 1528-2280-ND MFG: Adafruit Industries LLC / 3333 DESC: CIRCUIT PLAYGROUND EXPRESS
  2. Lithium-Ion Battery (1) PART: LIPO803860 MFG: Shenzhen Pkcell Battery Co. LTD DESC: LI-POLYMER BATTERY
  3. Vibration Motor Module DC (4) PART: GR-US-222 MFG: Daiko DESC: VIBRATING MOTOR MODULE DC
  4. Jumper Wires (M-F)
  5. Insulated Wire


  1. Conductive Thread PART: 1568-1804-ND MFG: SparkFun Electronics / DEV-13814 DESC: SMOOTH THREAD BOBBIN 12M (STAINLESS)
  2. Non- conductive Thread
  3. Solder Iron
  4. Knee Brace
  5. Heat Shrink
  6. Scissors
  7. Wire Stripper


Final Prototype Imagesvibrating-knee-brace

Demo Video

Development Images and Video

How it works up-close

Rapid Prototyping of Construction

In the first iteration of this prototype, the knee brace that I used had some restrictions of space and elasticity hence the circuit playground express would need added material i.e. a pocket to be placed which was not viable because the knee brace is multifunctional and can be used for intensive activities such as working out.


The second iteration was a better fit for the design I had in mind. The knee brace had good elasticity, as well as ample surface area, and was able to fit all the electronic components. However, the major issue I faced with this prototype was the wires which had to run across the knee brace but with the help of some elastic straps I added onto the brace I managed to tuck the wires away.




Circuit diagram


Code Hosted on GitHub

Project Context

Knee pain can be divided into three major categories:

During the time I would go for physiotherapy sessions to help with my grade 1 chondromalacia also known as runner’s knee I would undergo nerve stimulation using a Transelectrical Nerve Stimulator(TENS). Below is a brief explanation of how TENS inspired my design;


For my code, I was inspired by an Adafruit project the glowing LED team badge for Pokemon Go by Richard Albritton that uses the Circuit Playground to make someones own night-time safety + team spirit wearable. As it is quite difficult to show vibration on a wearable I opted to use the light emitted from the circuit playground express  NeoPixels to indicated the different vibration modes.  Another project that inspired my design idea is by Becky Stern a vibrating headband for timing meditation sessions. It uses a haptic motor controller that can execute different vibrational patterns such as waveforms, taps, clicks, fuzzes, hums, and bumps.


The idea of my device is to bridge the gap of convenience by introducing an alternative for physiotherapy that is on the go and can be used anywhere and the iTENS (see image above) does just this same job. It is a modern-day electrotherapy device that merges technology with the proven results of “TENS therapy” to provide effective and lasting pain relief via a simple medical device app. The iTENS uses a mobile app to operate an all wireless Bluetooth based electrotherapy device that is FDA-Cleared for over-the-counter use to combat pain.


Some of the challenges I experienced while working on this project include; connecting the vibrating motors to the circuit playground express as I was using three-pin motors the best option I had was to uses wires for the connection so that it is stable. Hiding the wiring was the main issue as well as placing the wires such that they do not cause distractions while the brace is in use. As a further iteration, I would perhaps look at different types of motors that require less wiring. Another challenge I faced in the initial iteration was the material I used to bridge the connection of the top and bottom straps of the knee brace elasticity is very crucial in this design which was something I came to learn later.


The circuit playground was easy to sew onto the knee brace and did not cause any obstructions while in use. The modification to bridge the top and bottom straps of the brace was a great addition. The connection used a battery hence it did not cause any obstruction with loose hanging wires and this made portability easy.

Further Study

Some things that I would like to revise in the project for further development include; changing the colour modes I used as I did not account for colour blindness in my study, perhaps the next version will use light intensity as opposed to colour. The next thing would be to have the circuit playground light up in different modes i.e. if the top motors are on then the top half of the NeoPixels light up. I would also like to build an app to help with the ease of changing the settings as well as add capacitive touch sensors instead of using a button in order to have each sensor have its own mode. I would also hope to incorporate some of the ideas from the iTENS company as well as adding more features such as heating pads and a timer to improve the efficiency of the device.


About iTENS, LLC. (n.d.). ITENS.

Glowing LED Team Badge for Pokemon Go. (2016, July 20). Adafruit Learning System.

HailiCare Health & Beauty. (n.d.). HailiCare Heated Knee Massager. HailiCare Health & Beauty.

Haptic Headband. (2015, November 25). Adafruit Learning System.

Johnson, M. I. (2007). Transcutaneous Electrical Nerve Stimulation (TENS) in Treatment of Mus. SpringerLink.

Knee Pain: How to Choose the Right Knee Brace for Your Child. (n.d.). HealthyChildren.Org.

Knee Pain Treatment, Causes, Remedies, Symptoms. (2021, February 24). MedicineNet.


Shoulder’s Feeling By Xin Zhang


Project Introduction

The main object of this prototype is to demonstrate an invisible sense that we perceive from the surroundings. The visible sense can be measured by and presented by two interfaces, which are wearable interface and a digital mobile interface. The wearable interface is based on an ordinary vest and be customized into the one embedded with pressure sensors on shoulders, and  the Arduino broad attached to the back of the vest. The pressure can be sensed when the user carrying a bag on their shoulders and this value will be delivered to a mobile-based interface. In this way, the user know the status change of invisible sense on their shoulders.The pressure values are divided into five intervals, and each of them has been represented by different phrases. The five phases are ‘easy’, ’comfortable’, ‘Ok’, ‘Hard’, ‘Can’t hold’, and each of them will be activated according to the pressure value read by sensors. Our physical body is considered as a non-verbal interface were embedded with a variety of biological sensors to generate the sense. However, people don’t perceive senses the same way, and our brain is selectively selective, these senses may be stored in our mussels, rather than deliver to our brain. In this sense, the external wearable device can help us to perceive the sense when we can read the feedback on the digital interface.

Experience Video

Key Image






Code link

Project Context

We generally have five senses( vision, hearing, smell, taste, and touch), and our physical body is a non-verbal interface and it offers a diagnostic interface rich with vital biological signals from the inner organs, blood vessels, muscles. For example, we could touch a piece of fabric to determine whether it was soft or hard, or on a tactile screen, people can use the gesture or pressing force to control the device. Moreover, there are more subtle senses that most people never really perceive. They are neuron sensors that can sense movement to control balance and the tilt of the head. Specific kinesthetic receptors exist for detecting stretching in muscles and tendons, helping people to keep track of their limbs. Once these sensors receiving the signals, they deliver these signals to the brain then the information will be translated into individual feelings. However, people don’t perceive senses the same way, and our brain is selectively selective. In other words, we are constantly failing to notice things right in front of us or the things that happened to us.

This is a common phenomenon, for example, our shoulders work as the main part to withstand external force when we carrying a bag or backpack. Imagine the scenario that you are carrying a heavy bag in a rush hour, it might easily ignore the tension on your shoulders until arrived at the destination. The time duration may also affect the sense in this process, like in the previous, we may not feel too much pressure on shoulders, and later, the capability for withstanding will decrease. At the same time, other factors may also affect the sense of force, like walking on a flat road or climbing a hill, our shoulders perceive the force of the bag will also be different. In this sense, it is essential to demonstrate the invisible sense with the help of external sensors which can accurately measure the value and deliver the information to a digital interface.

Those wearable devices, like smartwatches or bracelets, work as an external sensor to monitor the user-health condition, like heart rate, blood pressure, sleep quality.

As I concerned, the wearable can detect more information when they can better fit human fit and are closely associated with human interface. The ordinary vest is designed and manufactured based on human figures which means they are closely associated with our physical body. For that reason, I customized an ordinary vest into the wearable facilitated with digital components at the force point of the shoulders. Besides, e-textile and fabric-based wearable can also work more efficiently to detect the stretching in muscles and tendons and they can work as a highly flexible sensor to help people sense the physical change more easily without awareness like a bandage.

In the process of exploring the wearable interface, the following projects inspired me a lot, especially for customizing the non-functional fabrics into variable material which provides me lots of detailed solutions for further experiments.

The polySense:It applies a chemical process called in-situ polymerization to custom the ordinary non-functional material into sorts of e-textile material which sensing pressure, stretch, humidity, temperature, capability. One of the demonstrated examples is CCC leggings, the conductive undergarment at the knee can be used to measure the resistance changes so that reflecting the knee flex movements. Comparing with the wearable accessories like a watch or bracelet, the cloth can be closely associated with our physical body, which can constantly detect more subtle actions, like the forces on the joints and muscles which are invisible to people.

Divergence:It provides me another perspective to think about the context when taking the human body as an interface.  Literally, the interface is considered as a layer that provides users to communicate with the system, in a physical scenario, our body is a non-verbal communication interface that helps people to detect the signals from the surroundings, however, nature is filled with lots of ecologies which is beyond our human abilities. And this project proposes the creation of a wearable EMF detector that provides the human body with the ability to feel and hear the electrically and magnetically charged particles that propagate around us in the form of waves. These signals are also difficult to feel and detected by our biological sensors, so this project applied a fabric-based sensor to sense the invisible information from the environment.

eTextile matrix sensor :This is an open-source project created by Maurin Donneaud, who specialized in interaction design and physical computing. He has put a lot of work into making a large flexible touch-sensitive cloth. It features 30cm by 30 cm sensitivity that allows multi-touch sensing and pressure topographic analysis. It made out of conductive textile shaped in rows and columns and a layer of piezoresistive fabric and easy to use. From my perspective, this eTextile is easy to integrate with non-functional fabrics and will be more wearable when applied in practical use.


In the first stage, the challenge was on how to choose a propriety sensor that can read the force accurately. My prior plan was to use a ‘sandwich structured’ pad to reflect the force by a variable resistance. Using graphite pigments to transform ordinary sponges into conductive materials with variable resistance, however, the testing experiments showed that the pad is not stable in generating the signal after being pressed for a while, as the customized sponge could not generate significant analog value when it was squeezed for a long time without deformation. It is less reliable for practical use, especially for long time testing. Fortunately, I was inspired a lot by the projects above, especially the eTextile matrix sensor. Although there are still uncertainties in the experiment of making this fabric sensor, this solution is significant for improving the user experience in the wearable interface.


For this version, the digital interface was developed by P5.js and the way of sending messages over wifi is also limited its mobility. But I think the combination of the wearable interface with the mobile-based interface is a great start for designing the wearable. Most digital devices, they need cloud storage to store user information to support the further design of the product. And my solution of using the mobile-based interface is another sub-storage for storing the user history. In this sense, the mobile phone will not only work for presenting the information, but also for restoring our information.

Next steps

Further exploration will improve the user interaction from both the wearable interface and the digital interface. The first part is to improve the mobility and flexibility of the physical interface, and the second is to provide users more feedbacks on a digital interface, like solutions for dealing with shoulder pain. The detailed steps are as followed:

Wearable interface:

  1. The function of the current version was realized by Arduino Nano, which is difficult to integrate with a circuit on the fabric, the next steps will start with testing with other broads which are more mobile.
  2. Conducting experiments to find how dose time duration affects the force sense for users and visualizing the data into diagrams to demonstrate the relationships between them. (To maintain the same variables, the experiment will make other external factors, such as road conditions, consistent)
  3. Further testing also shows that the pressure sensor has a disadvantage in flexibility in practical use. As each individual have their habits in carrying bags, which may result in different force point at shoulders. To make it more capable for more users, I plan to try the solution mentioned in the third

Digital interface:

  1. Basing on the findings in the relationships between the time durations and forces sensing, the digital interface will also be improved in displaying more detailed feedbacks, like the solutions of adjusting the force point to avoid overload at a single shoulder or taking some exercise to release the tension at shoulders.
  2. In a real scenario, a voice reminder is more practical for a walking personal who is carrying the bag. Consider practical use, I plan to add a voice assistant to send instant notifications to users.