title: Parylene MEMS patency sensor for assessment of hydrocephalus shunt obstruction.
abstract: Neurosurgical ventricular shunts inserted to treat hydrocephalus experience a cumulative failure rate of 80 % over 12 years; obstruction is responsible for most failures with a majority occurring at the proximal catheter. Current diagnosis of shunt malfunction is imprecise and involves neuroimaging studies and shunt tapping, an invasive measurement of intracranial pressure and shunt patency. These patients often present emergently and a delay in care has dire consequences. A microelectromechanical systems (MEMS) patency sensor was developed to enable direct and quantitative tracking of shunt patency in order to detect proximal shunt occlusion prior to the development of clinical symptoms thereby avoiding delays in treatment. The sensor was fabricated on a flexible polymer substrate to eventually allow integration into a shunt. In this study, the sensor was packaged for use with external ventricular drainage systems for clinical validation. Insights into the transduction mechanism of the sensor were obtained. The impact of electrode size, clinically relevant temperatures and flows, and hydrogen peroxide (H2O2) plasma sterilization on sensor function were evaluated. Sensor performance in the presence of static and dynamic obstruction was demonstrated using 3 different models of obstruction. Electrode size was found to have a minimal effect on sensor performance and increased temperature and flow resulted in a slight decrease in the baseline impedance due to an increase in ionic mobility. However, sensor response did not vary within clinically relevant temperature and flow ranges. H2O2 plasma sterilization also had no effect on sensor performance. This low power and simple format sensor was developed with the intention of future integration into shunts for wireless monitoring of shunt state and more importantly, a more accurate and timely diagnosis of shunt failure.
authors: Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, 1042 Downey Way, DRB-140, Los Angeles, CA, 90089-1111, USA.
authors: Brian J
authors: BJ
authors: Kim
authors: Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, 1042 Downey Way, DRB-140, Los Angeles, CA, 90089-1111, USA.
authors: Willa
authors: W
authors: Jin
authors: Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, 1042 Downey Way, DRB-140, Los Angeles, CA, 90089-1111, USA.
authors: Alexander
authors: A
authors: Baldwin
authors: Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, 1042 Downey Way, DRB-140, Los Angeles, CA, 90089-1111, USA.
authors: Lawrence
authors: L
authors: Yu
authors: Department of Neurological Surgery, Keck School of Medicine, University of Southern California, 1200 North State St., Suite 3300, Los Angeles, CA, 90033, USA.
authors: Eisha
authors: E
authors: Christian
authors: Department of Neurological Surgery, Keck School of Medicine, University of Southern California, 1200 North State St., Suite 3300, Los Angeles, CA, 90033, USA.|Division of Neurosurgery, Children's Hospital Los Angeles, 4650 Sunset Blvd., MS #102, Los Angeles, CA, 90027, USA.
authors: Mark D
authors: MD
authors: Krieger
authors: Department of Neurological Surgery, Keck School of Medicine, University of Southern California, 1200 North State St., Suite 3300, Los Angeles, CA, 90033, USA.|Division of Neurosurgery, Children's Hospital Los Angeles, 4650 Sunset Blvd., MS #102, Los Angeles, CA, 90027, USA.
authors: J Gordon
authors: JG
authors: McComb
authors: Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, 1042 Downey Way, DRB-140, Los Angeles, CA, 90089-1111, USA. ellis.meng@usc.edu.|Ming Hsieh Department of Electrical Engineering, Viterbi School of Engineering, University of Southern California, 3651 Watt Way, VHE-602, Los Angeles, CA, 90089-0241, USA. ellis.meng@usc.edu.
authors: Ellis
authors: E
authors: Meng
mesh_terms: D004566:Electrodes; D004867:Equipment Design; D006849:Hydrocephalus / Q000601:surgery*; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation*; D011108:Polymers; D013242:Sterilization; D017287:Ventriculoperitoneal Shunt / Q000009:adverse effects*; D014992:Xylenes
chemical_list: D011108:Polymers; D014992:Xylenes; C011055:parylene
keywords: Hydrocephalus; Obstruction; Parylene C; Patency; Sensor