Angela, who is a Software Engineer, began exhibiting symptoms of Carpal Tunnel Syndrome several months ago. She researched the condition and tried several things to get rid of the symptoms: wearing a wrist brace at night, better posture when typing, taking breaks, etc. Unfortunately, none of these treatments were effective. The only remaining treatment option was for her to undergo wrist surgery, wherein the carpal tunnel is widened. However, this procedure is often only a temporary solution as the tendons will likely continue to inflame until they fill the new, larger tunnel. Since we could not effectively treat the symptoms, we concluded we should alter the environment which causes the condition.
We determined that the principal cause of this problem was her computer use. Interestingly, it is mousing, rather than typing, that causes the problem. As any person who plays a lot of first person shooter games knows, the culprit is repeated clicking of the mouse button. Given that Angela's job is to write software, and that a great deal of her free time is spent in front of a computer, it was not viable for her to stop using a computer. So we decided that we should replace the mouse input device.
It occurred to me that one could replace the mouse buttons with foot pedals. Even better would be to replace not only the buttons, but the movement input also. This would allow the user to utilize the mouse without moving his/her hands from the keyboard, resulting in greater efficiency. After taking apart some mice, it became clear that I could modify an existing mouse to meet this objective. A roller-ball mouse would not work because they get dirty enough on a table; a floor would render it inoperative quickly. But an optical mouse seemed to work fine.
I went through several ideas and a couple working models before I settled upon the present version.
On the left are the pedals which serve as mouse buttons, and the rightmost object is the movement input. I used Category-5 cable terminated in RJ-45 jacks, in other words, standard ethernet cabling, to connect the components because this makes it easiest to obtain custom length and color combinations. Angela's favorite color is pink. In use, the pedals are usually right next to each other, with a shorter cable connecting them. The wire to the right is a cable connecting the entire apparatus to the computer's USB port.
Here is a closeup of the movement input unit. The user rests her foot on the traction pad, then moves the entire unit by sliding her foot left/right/up/down. The bottom is sheet metal, which glides well on the typical high-density carpet found in offices. If you have a looser pile carpet, wood, or concrete surface, you can get a footmouse pad (nothing more than a small piece of the appropriate carpet). Given the lower dexterity people have with feet than with hands, the mouse takes more space on the floor than it would on a table. Angela reports that a 1 foot by 1 foot area works well. It is a good idea for the user to adjust her chair height so that her foot is comfortably resting on the pad.
These are the left and right button pedals. The user can rest her foot on the primary button, and a slight press of the foot results in a click input.
Here is a closeup view of the extremely complicated mouse button input unit. Can you guess how it works? The spring is what allows the user to rest his foot on the pad without actuating the button.
This side view of the pedal unit shows that I soldered the button terminals to a twisted-pair in the Cat-5 cable.
I attached the traction pad to the movement unit with velcro. You can remove this piece to reveal what looks suspiciously like an ordinary optical mouse, sans top. The original mouse is attached to the sheet metal with silicone.
I soldered two twisted pairs from the Cat-5 cable to the button terminals on the bottom of the board.
The bottom of the movement unit reveals the big trick....I used a dremel to cut a hole in the sheet metal to allow the optical tracking element to 'see' the floor. I found that the distance tolerance of the tracking element is very small (it can't be too far raised above the surface it reads), which is one of the reasons I chose to use sheet metal (very thin) for the footmouse frame. The sheet metal also offers very little friction when placed on a common office carpet. I sanded the sides of the bottom so that the metal doesn't snag on the rug as one moves the unit left and right.
I siliconed spiked feet to the bottom of each foot pedal, as shown above, to keep them from sliding across the floor.
Angela reports that the footmouse works very well. She has replaced her mice at work and at home with footmice. She says that people sometimes stop and look at her when they see both her hands typing on the keyboard while the mouse cursor is moving. Most important is that her carpal tunnel symptoms have completely disappeared! I consider this an incredible result, and I believe that there are many people who could benefit from a footmouse device.
Given that people usually don't use their feet for much aside from standing and propelling themselves, it takes some time to become adept at using the footmouse. However, once one gains the dexterity to use footmouse well, he can be more productive at the computer as he can type and perform mouse input concurrently. It took Angela two weeks to become completely comfortable with footmouse.
All of the components I used to build footmouse are easily obtained, except for perhaps the sheet metal. Unless you have a sheet metal break, you will have to go to a sheet metal shop for these pieces in order to cut them and bend them appropriately. It is also far less expensive to obtain the sheet metal at a sheet metal shop than at a hardware store. With optical mice selling for under $20 now, you should be able to obtain all the parts for making a footmouse for well under $50.
If you have any questions or comments about footmouse, you may email me at
Last updated 9 February 2009.