HCDE 451: TENSy Case Study

a final project for HCDE 451: user prototyping techniques

Duration

October 25, 2020 — December 11, 2020

Tools:

• OnShape, GoodNotes

Role:

• Solo project

Final Deliverable:

TENSy_Video

Concept:

Idea:

• TENSy is an IoT menstrual pain relief device that uses transcutaneous electrical nerve stimulation to ease pain and syncs pain data to an app on a user’s phone.

Motivation:

• Millions of people, myself included, suffer from menstrual pain. Additionally, many people suffer from menstrual conditions, such as endometriosis or PCOS without knowing. Some with these conditions continue living with intense menstrual pain thinking their level of pain is normal when it is not. A device that both tracks period pain and relieves period pain could help others who are unsure if they are experiencing abnormal pain levels.

Design:

• The TENSy design is inspired by existing menstrual pain relief TENS devices, such as Ovira and Livia. There is a main device with a power button and relief setting buttons, a wire component that gets plugged into the main device, and electrodes on the wires that help direct the pain relief on a user’s skin.

TENS devie, Livia, for mentrsutral pain design.

Goals:

The main goal of this prototype was to assess desirability of this proposed device. As this prototype was mainly done in the CAD software, OnShape, there was no real way to test usability or feasibility without access to a 3D printer. Desirability was the easiest goal to test.

The Beginnings:

TENSy started out as a digital 3D model in OnShape back in October. The original TENSy design was quite bulky:

first ever prototype with no feedback. I didn’t pay attention to the dimensions for the first prototype.

After the first initial round of critique, I decided to use the following steps to make revisions:

Steps for the 2nd Prototype:

1. Started with a circle sketch because I wanted to eventually make a cylindrical shape.
2. I then extruded the circle sketch to create a cylinder of 75 mm in height. In the original version, the cylinder was smaller in height. However, after doing some research on the dimensions of popular TENS menstrual devices, I decided to make the cylindrical shape taller.
3. On top of the cylinder on the front plane, I sketched a rectangle.
4. I then extruded the rectangle 15 mm as “remove” to create an outlet for the electrode USB cable.
5. I used the transform tool to move my extruded rectangle closer to the center of the circle because I wanted to make the top more round to match the bottom.
6. I used the fillet tool on the edge of extrude 1 with a circular radius of 9 mm. This was to even out the shape of the device.
7. Next, I used the fillet tool on the edge of the first extrude to get a rounder and smoother bottom of the device. This would ideally make it easier to place in a user’s pocket if they wished. Additionally, The fillet radius is 15 mm which is in between too round to stand up straight on its own and too clunky to fit into a pocket.
8. I then sketched another circle on the top plane of the cylindrical shape to create a power button for the device.
9. I extruded this circle outward by 21 mm from the center of the cylindrical shape so the button can be pushed.
10. I added another plane so that I could work on the clip-on part of the device
11. Next, I sketched an ellipse to act as a clip to attach TENSy onto pants.
12. For the final version, I used the fill tool to fill in the hook. I

2nd prototype based on feedback Dimensions were considered

However, even with these revisions there was still much more to do. The actual electrode wire component was missing from the original design!

Implementation of Finalized Prototype:

Sketching: Created rough sketches of my complete design concept

Rough sketches made in GoodNotes on the iPad

OnShape Revisions: Creating the Wire + Electrodes: I iterated upon my 2nd prototype to include the electrode component of the device. I used the following steps to do this:

1. Drawing an extruded circle of 50 mm diameter. This is approximately 2 inches in diameter, which can provide a decent amount of relief coverage.
2. Completing the circular disk by using a fillet to make the electrodes more pronounced.

one of the electrodes

2. Mirroring this disk to create the other electrode.

both electrodes side by side

3. Creating the USB-like wire by connecting a curved line and a straight line with the sweep function. I had trouble doing this function and didn’t know what it did. Thus, I asked a classmate for help and he was able to tell me what the sweep function did and how to use it. The wire has a rectangular component to represent a USB plug on the bottom that was created by an extruded rectangle 8 mm wide. This length will fit in the rectangular hole on top of the main device.

The USB like wire connects the two electrodes and is meant to be plugged into the main device.

OnShape Revisions: Revising Main Power Device

1. Adding pain level relief buttons — the first prototype didn’t allow users to change the amount of relief they felt. These buttons were originally 5 mm in depth, but I realized that seemed too big. After asking instructors during class, I adjusted the button depth to around 3 mm. These buttons are on the main power button because this button counted as an OnShape surface, whereas the curved cylindrical surface was not considered as a ‘surface’ in OnShape.

Front view of the TENSy device. Shows a ‘+’ and ‘-’ button to allow the user to increase or decrease the amount of pain relief they receive.

2. Refining the back clip — before the clip was just an oval attached to the back. I adjusted the prototype to have a circular hinge that can allow the clip to move outwards to attach on a user’s clothing. The oval clip matches the color of the device for more consistency.

Side view of the TENSy device. This profile view shows the depth of the pain relief buttons and the hinge for the clip.

Connecting it to Internet of Things:

After creating the CAD prototype, I created a brief wireframe in Figma to show how TENSy could sync period pain data to an app. A user can be told that their period pain levels are normal or irregular based on the amount of pain relief TENSy provided.

A person with cramps lying down. Two white circles are drawn to show where electrodes could be placed to alleviate pain. This app screen shows that a user’s pain levels are normal.

Evaluation

I evaluated my final prototype through a Google Form Survey. In the survey, participants are asked to watch the project explanation video for TENSy. Then they answer a few questions regarding the TENSy device, such as how likely they are to use it, what did they like about the device, what did they dislike etc.

Analysis

According to the survey results, most participants were somewhat unlikely to use the TENSy device. One participant did mention they would be somewhat likely to use the device because they suffer from cramps.

What went well:

• internet of things aspect was interesting
• it seems usable and desirable
• idea of tracking pain levels

What could be improved:

• making prototype more multipurpose pain relief rather than menstrual pain specific
• make the design less intimidating because the electrode concept was a bit scary
• specify error states in the video: where should the TENSy device be attached? Clothes? Could the electrodes be placed somewhere beyond the abdomen?
• Revising the plus / minus option to show what is the max pain relief a user can receive.

What would I do differently?:

• gather more survey participants for more feedback. I had a very limited sample size of 3 participants.
• explore the different textures that are available in OnShape to see how to make the device more friendly looking

Ovira is a company that creates TENS menstrual pain relief devices. For their device, they have gel stickies that can be connected to electrodes to make the electrodes less intimidating and easier to stay on the skin.

• explore textures that can be put on the electrode in OnShape. Many existing TENS units have “gel pads” that can be connected to electrodes to protect a user’s skin.
• explain and investigate the internet of things functionality some more in the prototype. If there were more time, I would create a brief digital prototype to show how pain relief is tracked over time.
• If I were to do this again during non-Covid times and had access to a 3D printer, I would revise the dimensions to make sure they were realistic.
• Finally, I would account for error states or potential misuse of the device!