Ultrasound-Interrogated Implantable Sensor for Intracranial Pressure Monitoring

Stanford University, Stanford CA

Investigators

Abstract

Project Summary Hydrocephalus is a disease characterized by excess cerebrospinal fluid (CSF) accumulation in the brain, leading to elevated intracranial pressure (ICP). Current treatment options include the surgical implantation of a shunt that relieves pressure by draining the excess CSF. However, almost 100% of implanted shunts fail within 10 years, resulting in a life-threatening condition necessitating additional surgery. Diagnosing shunt failure is challenging due to non-specific symptoms and the lack of non-invasive shunt patency measurement, resulting in unnecessary hospital visits and potential for permanent neurologic injury or death. ICP monitoring remains one of the most definitive ways of diagnosing shunt failure, yet current methods are either highly invasive or lack reliability. Thus, there is a critical need for a technology that enables ICP monitoring from directly within the ventricles in an accurate, reliable and non-invasive manner. This project will develop a passive, shunt-mountable ICP sensor that can be wirelessly interrogated with ultrasound in a safe, comfortable and reliable manner. This project’s workflow is structured into three distinct yet interrelated aims. Mathematical models and finite element simulations will be used to optimize the design an ICP sensor with high sensitivity and dynamic range. The optimized designs will be fabricated, and their performance evaluated in benchtop experiments (aim 1). A pre-clinical ultrasound system will be used to localize and wirelessly communicate with the sensor through a skull phantom in water tank measurements (aim 2). Finally, the sensor electronics will be miniaturized, and packaging will be optimized for implantable applications. The system will be tested in a hydrocephalus rodent model and the results will be benchmarked against a commercial ICP sensor (aim 3). The innovation lies in the pioneering use of acoustic frequency combs to sense and communicate ICP through the skull, from a fully passive, implanted microscale sensor. Significantly, the proposal advances a fundamentally new tool that will enable longitudinal, non-invasive and accurate ICP monitoring at the clinic or bedside using ultrasound, thus eliminating the need for costly imaging, additional surgery, and patient distress. The ability to reliably monitor ICP also provides access to a wealth of previously unavailable biometric data that might have broader applicability for surveillance of brain tumor recurrence or for monitoring of traumatic brain injuries. The K99 phase will provide dedicated training and career growth opportunities in implantable sensor development, ultrasound imaging, bioelectronics, animal study design, small animal imaging and other dedicated preparation needed to transition to a faculty position and an independent research career developing sensors for continuous health monitoring. These training activities will provide the skills necessary to complete the proposed sensor miniaturization, packaging and animal study in the R00 phase.