Problem Statement:
A device that will provide cyclic heating and cooling to minimize chronic joint pain in the hands of patients with arthritis.
Device Need
Currently, there is only low evidence to support the effectiveness of non-pharmacological and nonsurgical therapies for arthritis such as:
• Weight loss
• Exercise
• Assistive devices
Cyclic heating has been identified as a possible combination therapy regimen where:
Cooling → decreased pain
Heating → increased range of motion
Project Progress
September 12th – Physical Modeling/Device Requirement Considerations
We are currently determining our requirements based on the patient needs that have been identified. These requirements and their respective justifications will be presented next week to the class for constructive feedback.
We have also started discussing some possible methods of conducting tests utilizing a ballistics gelatin hand model with embedded temperature sensors. More to come on that later.
September 19th – Design Requirements Presentation
Described below are the requirements that were presented today.
Requirement #1
Requirement:
The device must be able to transfer heat to, and remove heat from the hand.
Justification:
Heat has been shown to increase range of motion. Cooling has been shown to decrease pain.
Requirement #2
Requirement:
The device must be able to monitor the skin temperature of the hand.
Justification:
The skin must remain below a certain temperature while heating and above a certain temperature while cooling to maintain patient comfort and treatment effectiveness.
Requirement #3
Requirement:
The device must be sized appropriately for optimal function.
Justification:
The device must fit comfortably on the average human male and female hand.
We received an abundance of feedback regarding our current requirements, but for aspects that we had not considered such as electrical safety, temperature fluctuations, and heating methods. All of these comments and concerns will greatly aid us in further developing our device requirements.
September 26th – Realistic Constraints and Standards
This week was dedicated to sourcing any standards that may apply to the functionality or design of our device’s intended use.
Below is a link to the constructed table of realistic constraints and relevant standards.
October 3rd – Requirements and Specifications
This week was spent further refining our requirements based off of the standards and constraints from the previous week.
Requirement #1
Requirement:
The device must be able to transfer heat to, and remove heat from the hand in controlled cycles consistent with literature for alleviating pain and increasing range of motion.
Justification:
Controlled heating has been shown to increase range of motion while controlled cooling has been shown to decrease pain. The application of cyclic heating and cooling for a set interval of time has been shown to achieve these therapeutic effects.
Requirement #2
Requirement:
The device must be able to monitor the skin temperature of the hand, specifically the fingers.
Justification:
The temperature of the skin must remain within the therapeutic range in order to provide a safe and effective therapy for the patient. Monitoring skin temperature will ensure that the device will not cause damage to the patient’s skin or tissue, as change in intramuscular and intra-articular temperature will not exceed that of skin temperature. The fingers are the part of the hand most susceptible to temperature change than the rest of the hand.
Requirement #3
Requirement:
The device must fit on the majority of human male and female hands.
Justification:
Female’s hands are on average smaller than male’s hands, while arthritis affects women more than men. A properly fitting device would be more effective at applying and removing heat from the patient’s hand.
Requirement #4
Requirement:
The device must be capable of being operated by the patient outside of a clinical setting with minimal training.
Justification:
Simple and intuitive design will allow patients to conduct the therapy outside of a clinical setting and without the need for a trained physician present. This will grant the patient therapeutic autonomy in personal locations.
Requirement #5
Requirement:
The device must be affordable for the target patient population.
Justification:
The patient population must be able to afford the device without financial compensation of active income as the target population consists largely of elderly individuals. Almost half of all Americans aged 65 or older and one third of Americans aged 45-65 have been diagnosed with some form of osteoarthritis.
October 10th – Gantt Chart and Budget Management
This week, we worked on making a Gantt chart to keep track of our goals and milestones over the course of the next year.
October 24th – Further Refining Device Requirements/Specifications
This week was spent finalizing our requirements and specification for the interim presentation next week.
October 31st – Interim Design Review Presentation
The requirements, specifications, and justifications presented at the interim design review are found on the page linked below.
Interim Requirements and Specifications
November 14th – Major Design Decision
This week marked a crucial point in our design process at which we decided to choose a convective heating/cooling system over conductive. In order to provide ample power for this change, the use of batteries was also replaced with a power outlet design.
November 28th – Final Design Considerations
Solidworks models were contructed for the device’s main chassis as well as heating and cooling circulation systems.
December 5th – Final Design Presentation for Fall 2018 Semester
We received a lot of valuable feedback in regards to our current design and will be working to implement as many reasonable changes and tweaks over winter break!
One of the most significant suggestions pertained to changing the method of circulating the warm and cool air. We will be looking into whether the peltier will be capable of switching polarities and shifting the temperature gradient quickly enough to only merit one main air circulating fan.
February 4th – Back in action and ready for testing!
Creating the silicone hand model was now the main concern in order to have plenty of time for data collection and device validation.
We talked with some other students that had experience working with silicone in order to determine the best way of creating this silicone hand. We came up with taking a 3D printed model of a human hand and pouring one type of silicone over it to create a negative mold. That mold would then be used to make the final silicone hand product. The approximate placement of the thermistors in the silicone hand are shown below.
We are also waiting on fans and power delivery components to start testing the peltier modules that we have and understand how much heat they really move.
February 11th – Starting Device Chassis Design
We are starting to design the chassis for the device that will house all of the components in Illustrator. We are using Illustrator so we can laser-cut the cardboard and do test fitting with the components before we cut the ABS sheets. (Important!)
Some additional research into which silicone product to use for the hand was also conducted. We wanted a material with a thermal conductivity closest to that of human skin. Luckily, Smooth-On provides technical data for many of their products and the Oomoo series silicone is appearing to be a promising possibility.
February 18th – Electrical Progress
Testing with the peltier has begun, however it appears that it will require a larger power supply to reach its full potential gradient. We will be looking into how hot and how cold the peltier can get with full power.
A modified model of a human hand was imported into Solidworks and will hopefully be 3D printed by the end of the week. The model used was downloaded from GrabCAD and was actually the skin layer of a multi-layered optical scan.
February 25th – Burning Cardboard and Peltiers
We believe our peltier module has burned out during testing, most likely due to a lack of cooling. The new motor driver used for power delivery works exceptionally well for providing ample current to the peltier, now we just need to make sure we can properly dissipate the heat!
The hand model has completed printing and the silicone pour will happen sometime this week. A section of the wrist was also cut to reduce the overall size of the model for the silicone mold pouring.
More cardboard is being laser-cut in order to confirm how large the dimensions of the chassis will need to be for the silicone hand to be placed inside. Other considerations such as passive cooling vents are also being cut. Additionally, the internal platforms and dividers for the components inside of the device are being designed in Solidworks to be cut from the ABS later this week.
March 4th – Silicone Hand Model Challenges
We ordered an anemometer to test airflow coming from the fan onto the hand. Hopefully this will help us understand how we want the user’s hand to be positioned in the device and where the sensors should be located.
Creating a box for the silicone hand model to be made has proved challenging. On previous attempts at pouring, the volume of silicone used was not enough to create a full mold and therefore multiple attempts had to be made. However, there was some success in making the mold and creating the first hand model without any thermistors embedded.
The ABS was laser-cut and now just needs to be cleaned and fit together. Additional peltier modules have also been ordered so if any more burn out, there will be extras to work with. We have also started using thermal paste rather than thermal tape for better heat movement from the peltier.
March 11th – Device Chassis Completed
With some small adjustments, the chassis of the device has now been assembled. The other components can now be test fitted and tweaked until their positions are exactly where we want them.
March 25th – Silicone Model with Thermistors Completed
The silicone hand with the embedded thermistors was also completed and testing in water baths will proceed later this week or next week.
April 1st – Data Collection
Thermistor data was collected for calibration purposes for the silicone model. Initial data collection has also begun and the procedures for testing are proceeding smoothly. The model is only being tested in warm and cool water baths at the moment, but once the electronic components are in the chassis, testing with air can begin.
April 8th – More Data Collection
Air flow in the device is being determined with the anemometer. This will help us determine how we want our airflow to be directed from the peltier with fans. Additional testing to see how well the peltier produces cool temperatures is ongoing.
Some safety features were completed such as an emergency stop switch to shut off power to the peltier, but keep the fans spinning. An LED was also added to provide a visual indication of when the device is on and operating.
More data from the water baths and silicone hand were also collected. This time, surface temperatures at set locations were also measured along with internal temperatures in an attempt to correlate the two parameters.
April 15th – Peltier Problems
We have a new heatsink and fan that are much beefier than the last ones, so we should be able to dissipate more heat and therefore produce even cooler air. The previous setup was not producing cool enough air to reach therapeutic ranges.
The device chassis is essentially all done and ready for the heating components to be secured.
April 29th – Final Device Design Completed
Testing of the silicone model in the completed device was conducted and some therapeutic temperatures were reached in the fingers closest to the fan. We suspect that improved heat exchange would allow the entire hand model to reach therapeutic temperatures. This is a possibility for future improvements and iterations.
May 6th – Final Presentation Preparations
We’re cleaning up the appearance of the device as much as possible without detracting from functionality for our final presentation.
Project Conclusion
Thank you to our project advisor, Dr. Brett BuSha for his guidance and mentorship during this senior design project. We’d like to additionally acknowledge Dr. Anthony Lau for his design support, Dr. Christopher Wagner for leading the class and offering feedback, Joseph Zanetti for technical support and machine shop training, Brian Witteritch for technical support and safety training, and lastly the TCNJ School of Engineering for funding and continued support.
Thank you for taking the time to read about our project! If you would like to see where we are now post-graduation, you can find links to our LinkedIn pages on the Contact Us page.