RESNA 26th International Annual Confence

Technology & Disability: Research, Design, Practice & Policy

June 19 to June 23, 2003
Atlanta, Georgia


Xin He, Zhiyu Zhu, Richard Goldberg
Department of Biomedical Engineering
University of North Carolina at Chapel Hill


Our client is a 3 year old girl with cerebral palsy. She has motor control problems, and her arms are very weak. Goal: To develop a device that uses auditory, visual, tactile and other stimuli to encourage the client to reach up and strengthen her arm muscles. Approach: we developed a freestanding wall, on which we mount four blocks. Each block provides different sensory stimulation, including blowing air, lights, and sound etc. These stimuli encourage the client to push, pull and reach up to play using his/her arms. Results: Each specially designed block provides unique combination of several types of stimuli. By mounting blocks in different positions, the device can be reassembled to provide varied pattern of stimuli. The modular design gives this device flexibility of reconfiguration. Conclusions: Using encouraging sensory stimulations, this device can help children with cerebral palsy to strengthen their muscles.


More than 500,000 people in the United States are affected by Cerebral Palsy. People suffering from cerebral palsy may have motor control problems, cognitive disabilities and impaired vision or hearing. An important treatment is physical, speech, and behavioral therapy. One goal of the therapy is to prevent the weakening or deterioration of muscles that can follow lack of use (called disuse atrophy) and avoiding contracture, in which muscles become fixed in a rigid, abnormal position.

Our client "Jenny" is a 3 year old girl with cerebral palsy. Her physical therapist is working on strengthening her arms, and in particular, her right hand. Her physical therapist wanted a device to encourage her to stretch her arms in front of her, which would strengthen her upper arms and trunk muscles. Although she has vision and hearing deficits, she enjoys sounds and flashing light, so this could serve as a positive stimulation.

There are some commercial toys available that could be used to strengthen muscles of children with disabilities. The problems with these devices are: they provide limited sensory stimulation and fixed stimulation mapping; most of them cannot be mounted vertically, thus the children do not have to reach up to trigger those switches; and for most commercial devices, all the sounds are already built in by the manufacturer, and the child cannot be creative to record her own sounds.


To develop a device that uses auditory, visual, tactile and other stimuli to encourage the client to reach up and strengthen her arm muscles. It should meet the following criteria:

  1. Stable: the device should not tip over when the client pushes and pulls with reasonable force.
  2. Appeal to children: the device should be visually attractive, interesting for children to play with.
  3. Flexible: the user's parent should have the option to rearrange the toys mounted on the wall. This feature helps keep the device interesting to the user.
  4. Expandable: the user should be able to add new features to it easily.


This device consists of three major parts: the frame, five function blocks, and the power supply. Any combination of four out of the five blocks can be mounted at one time. We applied very bright colors and simple shapes in designing this device to be attractive to children. A photo of this device is shown in figure 1.

Figure 1. Photo of the sound wall device.
Figure1:  This is a photo of the sound wall device.  It shows the supporting structure with 4 blocks.

Frame--A freestanding Wall. The frame consists of two parts, the frame and supporting structure. The frame and supporting structure can separate, so that the device is easily portable. The triangular structure of the supporting part makes it very stable.

Five function blocks

Motorcycle driving block: This block provides blowing air and flashing light stimulation. The client has to reach out to hold the motorcycle bar. Turning the bar left and right activates the lights and fans on each side.

Recorder block: There are two switches on this block, activated by pulling a cord. One switch is for recording a message, and the other one for playback. The purpose of this block is to encourage the client to pull a cord in order to record and play a message. It also allows the client to be creative. She can make any kind of sound she likes.

Telephone block: On this block, there are nine push bottons, which represent the 9 digits on a real telephone. By pushing the buttons, prerecorded music or a message is played from the speaker. Another feature of this block is the phone bar. We attached one set of magnets on the block and a corresponding set on the phone bar. As a result, the phone bar can be hang up on the block easily in one direction but not in the other direction. To play with this block, the client is encouraged to push different buttons, and to feel the strength of repulsion and attraction of magnets when hanging up the phone. The telephone on this block is adapted from a commercial toy phone.

Rotating flower: on this block, two different melodies can be played by either pulling two switches together or pushing two push buttons together. In addition, the flower rotates while either set of switches is activated. The speed of the rotation is controlable with a knob. The flower is made up of very soft fabric with plastic materials inside, so when it is touched, a crinkling sound can be heard. The client has to use both hands at the same time to get any music reward. So the design purpose of this block is to train muscles of both arms at the same time, and encourage cooperation between the two arms.

Velcro block: A music box is attached to this block, along with several Velcro strips. The user can customize this block by attaching toys or other items to the Velcro strips.

Power supply. We used a 110~12v transformer from RadioShack to provide 12 volt power supply.


All the circuits we designed and built are quite robust and stable and the client and her family have enjoyed using the device.

Safety Issues

Frame: The frame was built by UNC physics shop. It is made of aluminum, which is light but rigid. All the edges are hand sanded, so the edges are very smooth. Finally, the structure of the frame is quite stable.

Power: We built a jacket on back of the frame to provide 12 volts to each block. The power connector of each block is screwed in the jacket, which makes the connection very robust and safe.

Front of blocks: All exposed metal on the front of each block is grounded.

Back of blocks: All circuit boards are insulated into project boxes. All the wires are fixed on the board. We also covered the entire back panel so that nobody can play with the wires.


We believe this device can help "Jenny" to train her muscles. The major advantages of this device are: it is vertically mounted; it is expandable; "Jenny" can be creative while playing with it; and it is open-ended as any child can enjoy playing with it.

A major disadvantage of this device is that "Jenny" has to have supervision while using this device. A suggested future work is to build a custom chair for "Jenny" that can support her trunk, so that she can play alone.


UNC Physics shop, they helped us build a very stable frame.

Nancy Curtis, the therapist, her knowledge of our client help us a lot in our design.

Our client and her family, very lovely family, very kind parents and grandmother, very cute child.


Richard Goldberg
Department of Biomedical Engineering
University of North Carolina, CB #7575
Chapel Hill NC 27599

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