A Nanometer Resolution Wearable Wireless Medical Device for Non Invasive Intracranial Pressure Monitoring

Abstract

The non-invasive intracranial pressure (NIICP) method based on a skull deformation has been proven to be a significant tool for an assessment of the intracranial pressure (ICP) and compliance. Herein, we present the development and characterization of a novel wireless sensor that uses this method as its working principle and was designed to be easy to use, to have a high resolution, and to achieve a good accessibility. Initially, a brief review of the physiology fundamentals of the ICP and the historic evolution of the NIICP method are mentioned. The sensor architecture and the rationale for the chosen components are then presented, aiming to ensure nanometer displacement measurements, the conversion of analog resolution to digital at a high speed, the fewest amount of distortion, wireless communication, and signal calibration. The NIICP signal has a typical amplitude of 5 µm, and thus a resolution of at least 1% of this amplitude is required for an NIICP waveform analysis. We also demonstrate a 40-nm resolution of the sensor using a nanometric displacement test system that can also respond dynamically for NIICP signals from 50 to 180 bpm without any significant distortion (maximum deviation of P2/P1 ratio of 2.6%). The future applications for this device are broad and can enhance a clinical assessment of the intracranial dynamics.

From disease to noninvasive intracranial monitoring

“…These and other methods, as well as the advantages and limitations of each, are summarized in Table 1. The CSF tap test, a less invasive method, is also used widely in the clinical environment to determine ICP (cmH 2 O) [7][8][9][10] . In terms of noninvasive monitoring, several techniques have been developed, such as the use of transcranial Doppler, the measurement of the diameter of the optic nerve, and the use of biodegradable sensors.…”

“…In the last six years, Mascarenhas' s research group has published papers showing the effectiveness of their sensor in clinical practice and adult patients. At the same time, research has been undertaken into the pediatric use of the device [10][11][12][13][14][15][16][17][18][19] .…”

A Novel Noninvasive Technique for Intracranial Pressure Waveform Monitoring in Critical Care

“…The P2/P1 ratio was calculated by dividing the amplitudes of the two peaks. All B4C sensor data obtained is processed by an algorithm previously created from the synchronization of B4C signals with arterial blood pressure obtained from more than hundred thousand heartbeats [27]. As the cardiac cycle may be overlapped with the respiratory cycle [29], this automated system indicate where P2 should be depicted on the waveform, instead of where it appears on the spectrum [29] (Figure 3).…”

“…As the cardiac cycle may be overlapped with the respiratory cycle [29], this automated system indicate where P2 should be depicted on the waveform, instead of where it appears on the spectrum [29] (Figure 3). Comprehensive explanation of B4C system functioning has been published [27].…”

Noninvasive intracranial pressure monitoring in women with migraine

“…Another non-invasive method was recently developed and validated 12 – 14 . This method considers an extracranial strain gauge sensor that, when positioned in the frontolateral region, detects small variations in cranial deformation induced by intracranial pressure waveforms 14 , 15 . This Food and Drug Administration (FDA)-cleared non-invasive sensor and software to record the variations induced by intracranial pressure waveforms and convert them into numerical values that can be interpreted in real time or analyzed later 14 , 15 .…”