Real-Time Monitor of Neurotrauma Patients Replaces Bulky Equipment

R&D DIGEST

In addition to providing real-time monitoring of traumatic brain injuries, a multitasking lab-on-a-tube reduces the need for additional monitoring devices. Researchers at the University of Cincinnati (UC) have developed a multimodal tube prototype, or smart sensor. The device is capable of continuously monitoring physiological and metabolic parameters, draining cerebrospinal fluid from an injured brain, and delivering medications to patients, according to a UC press release.

Traumatic brain injury is usually followed by secondary injury, which is caused by such factors as swelling, increased intracranial pressure, and lack of oxygen, UC researchers say. No medicine exists to reduce secondary injury, so real-time monitoring of the brain is one of the best ways for doctors to help patients.
“When we can track what is going on in a patient's brain tissue, or blood, on a continuous basis, we can treat the patient much more promptly and effectively,” says Raj Narayan, MD, chairman of UC's department of neurosurgery.
To make the device, researchers developed a membrane-type resonant piezoelectric pressure sensor on PVDF-TrFE (polyvinylidene fluoride trifluoroethylene) film. Then glucose, oxygen, and temperature sensors were fabricated on 25-μm-thick Kapton film, says Chunyan Li, PhD, designer of the prototype and a postdoctoral fellow at the UC department of neurosurgery. Parylene microchannels were also fabricated by stamp-and-stick bonding of patterned parylene film. Finally, all of these components were stocked, bonded, and rolled spirally to form a tube structure.
As a result of the design, the smart sensor can simultaneously monitor intracranial glucose, oxygen, temperature, and pressure. The research team has discussed adding other modalities to it. Possibilities include intracranial sodium, osmolality, lactate, and pyruvate, says Lori Shutter, MD, director of neurocritical care at the UC Neuroscience Institute. Shutter helped drive the lab-on-a-tube project by expressing the need for an improved device.
Currently, advanced neuromonitoring requires four or five different incranial devices. By integrating the functions of all of these devices into one unit, the lab-on-a-tube simplifies the complex process of managing patients, Shutter says. It also offers a more economical treatment.
Another advantage that the lab-on-a-tube option provides is that only one hole—instead of the typical two or more—must be drilled into a patient's skull to insert the sensors. Additionally, the tube's diameter can be expanded or contracted. The anatomy of every person varies; therefore, a device that offers a variable length enables modifications to “allow for patient movements, other devices, and connections to bedside monitors without excessive material that could get tacked on during routine patient-care activities,” Shutter says.
The original prototype measured 1.7 mm in diameter and 11 cm in length, but the team is working to make it smaller. They have submitted an application to perform animal trials, and have filed a provisional patent.
Frank Mayfield, a professor in the department of neurosurgery, is principal investigator of the lab-on-a-tube project. Pei-Ming Wu, WooSeok Jung, and Chong Ahn, PhD, all of the Microsystems and BioMEMS Laboratory, contributed to the project.
The researchers received support from the Integra Lifesciences Foundation (Plainsboro, NJ). Their lab-on-a-tube was profiled in the July issue of Lab on a Chip.

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