The University of North Carolina at Chapel Hill

Designers: Dan Cooney and Brian Rucker
Supervising Professor: Dr. Richard Goldberg

INTRODUCTION:

An infant patting device was developed to simulate a hand patting motion during bottle-feeding in the Neonatal Intensive Care Unit (NICU). A hand patting motion calms the baby to facilitate bottle-feeding. It may also decrease the probability of food aspiration into the lungs during feeding. This device provides an easy, safe way to comfort the patients in the NICU, while providing relief to their caregivers.

Fig 1: Infant Patting Device

SUMMARY OF IMPACT:

Some NICU infants require two nurses to feed them: one to hold the infant and the bottle, and another to pat the infant’s back. This device performs the patting task, allowing a single nurse to manage all feeding tasks in a safe and timely manner. The patting, used independently of feeding, may allow the infant to remain calmer for the duration of the stay in the NICU. Currently the device is waiting for clinical approval.

TECHNICAL DESCRIPTION:

The system works by providing puffs of compressed air to an inflatable bladder that is held up to the infant. Compressed air sources are available throughout the NICU. An air input hose connects this air source to the system. A timer circuit turns a solenoid valve on and off to provide puffs of air. These puffs flow along the air output hose (25 ft. long, ½” inner diameter) to the inflatable bladder that provides the patting motion. The bladder can be suspended in foam padding or placed directly on the infant. An escape hose attaches to the bladder to direct the airflow out of the bladder and away from the baby.

The system is encased in an aluminum project box (12” x 12” x 8”) equipped with wheels to facilitate movement. There is a power switch, as well as large knobs that allow the user to control the air pressure and patting rate. A commercial 24V wall transformer provides electrical power. Throughout the system, ½” diameter tubing is used, which is large enough so that it does not restrict air flow.

Fig. 2: System Block diagram

The puffs of air are provided by a pressure regulator, timer circuit, and solenoid valve. Since the compressed air source has a pressure of 60-85 pounds per square inch (psi), a regulator is necessary to lower the pressure. The user can adjust the regulator output pressure to the range of 2-60 psi. A solenoid valve opens and closes to provide puffs of air to the inflatable bladder. The solenoid has a large 5/8” aperture to maximize the flow of air, and runs off a standard 24V plug in power supply. In order to switch the solenoid on and off, a 556 timer circuit is used. This timer uses a 5V power supply, which is provided using a 24VDC to 5VDC voltage regulator. The frequency at which the timer operates in controlled by a potentiometer, which can be adjusted using the frequency knob on the box.

The patting motion is provided using a custom neoprene bladder. The bladder is circular with 3 ½” diameter and has connections for an air supply hose and air escape hose.

Fig. 3: Neoprene Bladder

When the valve is open, the puff of air from the solenoid causes the bladder to expand. The air leaves the bladder passively through an open tube. The tubing is 25ft long to enable the nurses to freely move with the device, and to ensure that the air released from the bladder flows away from the infant.

Safety was the most important feature to address. The system needed to be safe for use with infants, and easy to clean and sterilize. The metal box provides an effective casing for the electrical equipment, and effectively separates the infant and the caregiver from the electrical circuits. Neoprene was chosen for the bladder to avoid any possible side effects from latex allergies.

Aesthetic concerns were addressed by decorating the plain aluminum box with child friendly, decorative Sesame Street® stickers.

The total cost of this project was $667.