# iPPSIS: implanted Passive Pressure Sensor Interrogated with (ultra)-Sound

> **NIH NIH R21** · EMORY UNIVERSITY · 2021 · $450,081

## Abstract

PROJECT SUMMARY/ABSTRACT
Changes to cerebral spinal fluid flow (CSF) dynamics may occur with traumatic brain injury, subarachnoid
and/or intraventricular hemorrhage, brain neoplasms, or central nervous system infection, and can all lead to
increased intracranial pressure (ICP). Neurosurgeons treat elevated ICP by placing a ventricular shunt, which
allows excess CSF to drain, thereby relieving the pressure on the brain. Over 50% of shunts fail in the first
year, and all shunts fail eventually. Shunt failure most commonly occurs in children under the age of 1 year and
accounts for over $1 billion in hospital admission costs. Unfortunately, verifying that a patient has a shunt
dysfunction is particularly difficult in young patients, as symptoms are non-specific (headache, nausea, or
fatigue) and existing non-invasive tests (MRI and CT) are costly and do not directly measure pressure. Only
46% of shunt patients presenting with these symptoms have a dysfunction, while the remaining patients incur
unnecessary expense, exposure to radiation, or invasive investigations that may result in brain injury. To
address this issue, we propose to create iPPSIS (implanted Passive Pressure Sensors Interrogated with (ultra)
Sound), which is composed of a passive, microfabricated pressure sensor “target” that deflects in response to
increased pressure and can be quantitatively measured with ultrasound. We hypothesized that rethinking the
current approach to wireless pressure sensors and removing the dependence on RF telemetry would lead to a
wireless sensor that is passive (no batteries), MRI compatible, and stable for long-term clinical monitoring
(years). As requested in the FOA, no unpublished preliminary data is included. However, our analytical
calculations of both the microfabricated target design and ultrasound resolution, which are grounded in
decades of research, demonstrate feasibility and a high probability of success. We will initially design iPPSIS
for pediatric populations given the significant need and lower technical barriers due to the reduced skull
thickness. The sensor will be implanted subdurally through a standard burr hole during a shunt placement
procedure, and will continue to operate as the patient's skull heals and reforms. Aim 1 focuses on the
construction and characterization of a novel, extremely stable, metallic micro-pressure sensor that will be
highly impervious to the physiological “harsh environment”. Aim 2 focuses on the testing of a novel operator-
independent ultrasound measurements and a new wearable ultrasonic transducer that would enable long-term
continuous monitoring. Aim 3 seeks to rigorously test iPPSIS in vitro as well collect in vivo feasibility data in a
porcine tumor model (n=2) that experiences rapid ICP changes over several months. Attesting to the rigor of
our approach, we have assembled a team of individuals with expertise spanning micro-electro-mechanical
systems design, ultrasound, neurosurgery, and in vivo porcin...

## Key facts

- **NIH application ID:** 10196310
- **Project number:** 1R21EB031545-01
- **Recipient organization:** EMORY UNIVERSITY
- **Principal Investigator:** Brooks D Lindsey
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $450,081
- **Award type:** 1
- **Project period:** 2021-08-01 → 2024-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10196310

## Citation

> US National Institutes of Health, RePORTER application 10196310, iPPSIS: implanted Passive Pressure Sensor Interrogated with (ultra)-Sound (1R21EB031545-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10196310. Licensed CC0.

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