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Ergonomics

Perfect fit

New kind of mouse provides more comfort and prevents muscular pains

Pains in the hands, in the arms and even in the neck brought about by repetitive intense movements in the use of the computer led to physician Luiz Cesar Peres designing a new kind of mouse, to diminish the physical impacts relating to the conventional model of this small apparatus. The way of manipulating the new mouse developed and patented by him is similar to the way used in writing, like a pen or a pencil, which makes for less physical effort and for more comfort. The first experiments with the prototypes, made by the doctor himself, showed far less harmful effects on joints, tendons and muscles. Peres is a professor of the Pathology Department of the Ribeirão Preto School of Medicine of the University of  São Paulo (USP), responsible for the discipline of Pediatric Pathology, and he got the pains while he was working on his professorial thesis and on the formation of a database on pediatric autopsies, in a two-year period between 1998 and 2000.

“During the work, I began to get strong pains in the hand and in the wrist, and I decided to make modifications to the conventional mouse”, says Peres. The first attempt was to stick a glue stick on top of the device, so that the hand stayed in a lever position, more upright and without moving much. “My intention was chiefly to prevent my hand from being bent backwards, with the muscles and tendons contracted, and to reduce fatigue and muscular torsions. I noticed that the glue stick on the mouse would improve the pain and did not cause the forced positioning of the hand.”

But mouses with glue sticks stuck on top are not at all practical. From this, and from the wish to make this idea evolve, Peres imagined an ergonomic mouse that could help millions of persons who suffer from the same ailment, called Work-Related Musculoskeletal Disorders (WMSD) or Repetitive Strain Injury (RSI), one of the main causes of leave of absence from work all over the world. In Brazil alone there are over 500 thousand cases a year. With the idea in his head, Peres, in 2001, asked a physiotherapist, then his future student for a master’s degree and currently already studying for a doctorate at the same university, Paulo Roberto Veiga Quemelo, for him to study the making of the new mouse.

Strong thumb
The first molds were made with papier-mâché and modeling clay until arriving at the final form, with a base and a mobile stick, like a joystick for electronic games, with the diameter of a pen. There are two directional buttons that are located on the stick, and they are activated by the thumb. “This is the strongest finger and the least susceptible to tiredness”, Peres explains. The stick is moveable only until the user adapts it to the best position for comfort, and it is locked afterwards. “This detail facilitates individual use, both for the right-handed and the left-handed.” The design of the base is irregular and appropriate to fit the hand, which is supported laterally and more suitably, with the plumpest part, the so-called hypothenar region, on the desktop.

The final lines of the new mouse were achieved with the collaboration of Professor Carlos Graeff, from USP’s Physics Department in Ribeirão Preto. “He has a laboratory where we were able to draw up the functional model of the new muse, with regard to the electronic part.” Accordingly, Peres, Quemelo and Graeff solved minor functional problems and finalized the first prototypes. At the moment, there are already ten, and they have optical technology. They can work with or without a cord, and the movement of the cursor on the screen of the computer is determined by a signal of light on the base of the apparatus, which lights up when it is moved in relation to the desk.

The next stage of the development of the new mouse is the stage of clinical tests, which will be carried out this year in the neurophysiology sector of the Ribeirão Preto Hospital and Clinics, under the coordination of Professor Wilson Marques Júnior. There will be 50 people without any physical problems who are going to perform various tasks on the computer using conventional mouses and the new one, on alternate days.

Muscular movement
Under the skin of the arms, above the muscles, electrodes will be installed to record the muscular movement. “We are going to analyze the contraction of the muscles in accordance with the electric current that passes through them and to the nervous system. We are also going to see the angles produced by the hands of the users when they are using the two kinds of mouse.” Afterwards, the volunteers are going to answer questionnaires for an evaluation of the degree of adaptability, comfort and security.

In the second stage of the clinical tests, patients with various kinds of physical problem will be investigated, ranging from people with RSI and WMSD to those who have had fingers amputated. “Afterwards, we will carry out other studies that have not yet been defined.” This work is going to group together mainly pupils from USP’s recently created undergraduate physiotherapy course in Ribeirão Preto. “It is worth stressing that all these research have an academic nature, because the mouse can already be produced and marketed”, says Peres. Although it has already attracted the attention of a few companies, none has yet manifested a concrete interest in licensing the product.

The final cost of the devices, estimated by its creators, should be equal or similar to the optical mouses on the market, between R$ 30 and R$ 40. “There are no great difficulties in manufacture, in relation to other mouses. The most sensitive part is the stick with the buttons”, Peres explains. The new apparatus, which does not yet have a name defined, is an object of desire of all those who know it, particularly the professors and staff of USP in Ribeirão Preto.

The Project
Development of an ergonomic mouse for computer based on the biomechanics of writing
Modality
Intellectual Property Support Program (Papi)
Coordinator
Luiz Cesar Peres – USP
Investment
R$ 6,000.00 (FAPESP)

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