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Sensor would catch extra pressure in baby heads

Sammi Lu and Tensae Assefa work with the sensor and a mannequin. (Credit: Jeff Fitlow/Rice)

The feel of the soft spot on top of a baby’s head can signal too much pressure inside, but a new monitor offers more comprehensive data without an invasive procedure.

Rice University students, working with Texas Children’s Hospital doctors at Rice’s Oshman Engineering Design Kitchen, designed the seemingly simple but sophisticated system to monitor high intracranial pressure (ICP) within the skulls of infants. The condition affects more than 400,000 babies every year.

Trauma in the brain can cause ICP, which is a marker for hydrocephalus, a buildup of excess cerebral spinal fluid within the brain’s ventricles.

The monitor, dubbed Bend-Aid, combines an old-school adhesive bandage with a sensor that has the potential to replace two current techniques: Palpating the child’s soft spot to get a general sense of pressure, or drilling into the skull to insert an accurate but highly invasive sensor.

The non-invasive method allows clinicians to monitor babies for as long as necessary to build a record of intracranial pressure over time.

“What physicians usually do is feel the soft spot where the skull hasn’t fused together yet,” says team member Patricia Thai. “If it’s tense, that’s a sign of higher pressure. If it’s sunken, it’s low pressure.

“But it’s really subjective between doctors and previous research showed it’s not very accurate. There’s a need for a quantitative and continuous method to measure pressure in the skulls of infants, to see changes in ICP over time.”

The student researchers embedded a soft, ribbon-like sensor with a 2.2-inch working length into a bandage that, when affixed to the baby’s head, reports to a data processor when bent in or out by the changing shape of the soft spot, called the fontanelle. The fontanelle generally closes after 18 months as skull plates fuse.

The students discovered a correlation of ICP levels within the skull pace and the bending level of the fontanelle and used that data to build a mathematical model that correlates the sensor’s bending angle to standard measures of ICP.

The sensor feeds a processing unit that displays the numerical pressure level on an LCD screen—and the system stores data on an external SD card for later interpretation.

“In actual cases, prolonged levels of ICP are more problematic than random spikes,” says team member Sammi Lu. “So we’ve built in an alarm system through LED lights and a buzzer.”

The bandages, already in common use to dress wounds, stayed put, even during exercise and showering—and in ideal conditions, the sensor’s accuracy remained consistent over time, according to the students.

Sabia Abidi, a postdoctoral teaching fellow in bioengineering at Rice, advised the students. Sandi Lam, a pediatric neurosurgeon at Texas Children’s Hospital, and Vijay Ravindra, a pediatric neurosurgery fellow at Texas Children’s Hospital, worked with the team.

Source: Rice University