DESIGN OF A DEVICE TO ALLEVIATE HAND TREMORS
A significant portion of the population suffers from hand tremors. This uncontrollable shaking makes for difficult use of small personal tools, reducing a person’s self confidence and efficacy in performing simple daily activities, such as brushing teeth, brushing hair, or applying makeup. While there are current devices on the market to counteract tremor interference, most of them only apply to eating and writing utensils, and they can get very expensive. We have designed a weighted tool sleeve that which allows this population to use their own variety of personal tools by reducing the effects of tremors. Upon creating and testing the prototype, we have concluded that our design satisfactorily reduces the effects of moderate to severe tremors, can be adjusted to fit a range of tool sizes, allows for a variable device weight, and is waterproof. The handle enables individuals with tremors to carry out activities of daily living independently and confidently, at a very low cost.
Design
To create a sleeve for a variety of tools, a method of how to account for different tool diameters had to be created. The device has an “umbrella” design, where the fabric folds and wraps around the standing tool. A water-resistant fabric is cut into a circle and sixteen seams are sewn in, equally spaced from each other for weight symmetry, coming out of the center of the circle. These seams create eight pockets, where cylindrical packets of lead shot can be slid in. The user can choose to insert a weighted cylinder, or an empty one, in order to maintain the shape of the device. This way, the users can choose the amount of weight they put into the device, depending on the severity of their tremors, their age, or the weight of the tool itself. The lead shot was chosen in order to have a better fit around a contoured tool handle which changes in diameter, rather than a rod of metal, which will stay straight. The length of these cylinders is 10 cm, close to the width of an average-sized hand. The diameter of the cylinders will be around 8-10 mm, in order to provide enough volume for the lead shot to be filled.
Tool Insertion
The prototype was tested with a variety of tools, including toothbrushes, hairbrushes, makeup brushes, razors, writing utensils, mascara wands, and a screwdriver. These tools all had a variety of handle lengths, widths, and shapes, which allowed us to test the universality of the design. Fit was tested by the project team and rated on a scale from 1 to 5, with 1 corresponding to poor fit and 5 corresponding to great fit.
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The most successful tools were the razors, with ratings of 5 for all three of those tested. These tools had very minimal slippage when pushed or pulled while in the device, likely due to the contoured shapes and rubbery material on the handles. The toothbrushes and hairbrushes were also quite successful, since most of the toothbrushes were contoured and rubbery, and the hair brushes had rubber handles.
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The makeup brushes rated between a 3 and a 4 for fit. While they fit well in the device, they were prone to slipping if too much pressure was applied since they had very smooth surfaces. In addition, since they had very small diameters, it was difficult to keep them in the center of the device. However, they were still able to be used effectively.
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The toothbrushes, hairbrushes, razors, and makeup brushes were the four tools that we indicated in our design specifications. All of these tools rated above a 3, so our design specification was successfully met.
The other tools that we tested included two mascara brushes, a sharpie, a screwdriver, and a pen. The mascara brushes both failed due to the very small size of their handles. The sharpie and pen both worked well, but they were a bit unstable in comparison with normal writing. The screwdriver was very stable and would not slip if turned. This was likely due to the larger diameter and rubbery surface on the handle.
Patient Experience
The prototype was tested by three tremor patients, each of whom had different tremor extremity levels. One was a patient with severe essential tremor, another had a mild tremor from Parkinson's disease, and the third suffered from very severe tremor from Dystonia. Weighted tools are most effective in patients with moderate to severe tremor, so we hypothesized that the patient with severe tremor would experience the most significant reduction in tremor.
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The patients rated the prototype based on ease of tool insertion, comfort, and similarity to normal use. All of the tools rated a 4 or 5 for ease of insertion, while comfort averaged a 3.78 and similarity to normal use averaged a 3.67. Only one of the participants used a makeup brush, and rated it rather low on comfort and similarity to normal use. The average overall ratings for each tool was 4 for toothbrush, 2.67 for makeup brush, 4.11 for hair brush, and 4.5 for razor.
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We also asked the participants to rate the ease of changing the weights. The weight of the handle ranged from 300g to 508g, which is close the range of weight shown to effectively reduce tremors (480g to 600g). The three participants rated the ease of weight alteration 4, 5, and 5, respectively. However, the participants reported that they did not perceive a great difference in use as they adjusted the weights.
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The average rating for tremor reduction across all of the tools was a 3. This was less favorable than the other aspects of the device, such as tool and weight adjustability. Specifically, the tools rated an average of 2.33 for toothbrush, 2 for makeup brush, 3.67 for hair brush, and 3.5 for razor.
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Participant 1 rated their tremor reduction an average of 4.33, participant 2 rated a 2.33, and participant 3 rated a 2.33. This is important to note, since participant 1 was the only subject who fell within our target severity range. Participants 2 and 3 were outside of this range, with a mild and very severe tremor, respectively. While we would need more testing to determine if our tremor reduction goal was met, this is an important observation.
There are many adjustments that we would like to make in future iterations of this design. Our first adjustment would be to change the "open" design to be already mostly closed. The completely flat design made it slightly difficult for the patients to insert the tools, and there was an excess of fabric that made the velcro difficult to close thanks to the umbrella-like design. We also would have made the adjustable weights heavier to allow for a greater change in weight.