Sensory Stimulation Center

Designers: Elaine Hsieh, Wesley Joe, and Anna Fernandez
Client Coordinators: Mary Caldwell and Lenore Champion, Duke Hospital Pediatric Rehabilitation Center
Supervising Professor: Dr. Larry N. Bohs

A Sensory Stimulation Activity Center (SSAC) was developed for use at the Duke Hospital Pediatric Rehabilitation Center. The SSAC is used to aid in the treatment of children under three with Down’s Syndrome or closed head injury. Studies suggest that sensory stimulation helps to promote development in these children. Most existing sensory stimulation activity centers are costly, only stimulate up to three senses, and are housed in simple plastic boxes. Housing this activity center in a stuffed bear and stimulating visual, auditory, olfactory, and tactile senses provides patient interaction and enjoyment. The bear interacts with the child by coordinating button activation to sensory stimulation in a cause-effect relationship.
How this project helped
The bear is visually appealing and fun to play with for children of varying motor skills, allowing them to enjoy themselves while learning cause-effect relationships under the supervision of a therapist. According to two therapists who use the SSAC:

“The Pooh is so colorful and friendly that all of my children want to keep him for their own. The Pooh helps the most with our physically and visually impaired children. These children are not given the normal access to exploratory play that physically normal children do. Because of that, they are unable to learn independently as other kids do. We use Pooh to stimulate the senses of smell, sight, sound, and touch.” -Mary Caldwell.

“This is a much-needed toy. It will definitely be very useful to our therapy of these children. Currently, similar products make the kids easily bored. This toy not only keeps their attention but is also very cuddly and fun to play with. So far, feedback has been extremely positive.” -Lenore Champion.

The active components of the device are housed in a stuffed bear. The SSAC is powered by 2 “C” batteries connected in series. A control panel on the bear provides the user interface for activation of the stimulation activities.

Activation of the functions is through momentary contact, normally-open push-button switches mounted on the control panel. The buttons have different colors and shapes. Adjacent to each button is a picture and a light emitting diode (LED) with the same color scheme as the button. Each of the four buttons, lights, and pictures are grouped to a stimulation activity: releasing scented air, blowing air, vibrating the arm, and playing music. The picture located next to each button represents the activity powered when the button is pressed. When a button is pressed and held the adjacent LED illuminates and the function is activated. When the button is released the function stops immediately. This is intended to promote the development of cause-effect relationships.

Each button is connected to the power supply via the main power switch (see Figure 2).. In parallel with each button is a 1/8″ jack for an external switch. This allows either the control panel button or the external switch to activate each function. In series with each button is the corresponding LED and a current limiting resistor. The components for the stimulation activity functions are activated in parallel to the LED circuits.

The control panel is made of plastic reinforced by ¼” acrylic sheets. Items on the front face of the panel are mounted onto the plastic control panel and on the acrylic sheet reinforcement. All circuitry is housed within the control panel box. Circuit components are soldered onto a perforated circuit board.

For the smell activity, a forked tube allows the passage of air from the box to the outside of the mouth. A removable air freshener cartridge housed in an isolated chamber provides scented air. While the activity is not on, a plastic flap blocks the smell from the tube leading to the mouth. When the button is pressed, a voltage pulse from a monostable multivibrator (74HC221A) causes a motor to raise the flap exposing the tube. A fan then blows the scented air out to the mouth. When the button is released, the multivibrator emits another pulse, the motor returns the flap to its closed position, and the fan turns off. This circuit is shown in Figure 3.

A box located inside the bear’s head contains the components for the smell and air blowing functions (see Figure 4). A centrifugal fan was built to maximize airflow through the bear’s mouth. A vibration unit was constructed using a motor spinning an off-center mass in order to produce a shaking effect when mounted in the bear’s arm. The unit is housed entirely in PVC plastic to increase robustness and safety.

The musical component comes from a commercial toy that plays a melody for a specific time when squeezed. The component was modified to play continuously when powered by the button. A piezo speaker from the same toy is mounted near the surface of the bear’s fur.

The approximate cost of the Sensory Stimulation Activity Center was $340.

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