What is hydrocephalus, and why is wireless intracranial pressure (ICP) monitoring being developed?

Hydrocephalus is a condition marked by increased pressure within the brain due to fluid accumulation, particularly affecting newborns. Current methods of monitoring intracranial pressure (ICP) often use catheters, but these carry risks like infection and hemorrhage. Wireless ICP monitoring aims to reduce these risks and improve patient care by offering a less invasive alternative.

What are the key differences between active and passive wireless ICP sensors, and why are passive sensors preferred for long-term monitoring?

Wireless ICP sensors can be either active or passive. Active sensors offer advantages like longer communication distances and improved signal-to-noise ratio (SNR), but they need a power supply, which increases their size and weight and necessitates periodic battery replacement, making them less suitable for long-term use. Passive resonant sensors, based on tank circuits, are better suited for long-term implantation with minimal disturbance to surrounding tissues.

What are the key components and functionality of the novel wireless intracranial pressure readout circuit presented in the IEEE Transactions on Biomedical Circuits and Systems study?

The novel wireless intracranial pressure readout circuit designed by Fa Wang, Xuan Zhang, Mehdi Shokoueinejad, Bermans J. Iskandar, Joshua E. Medow, and John G. Webster includes an implantable passive sensor and an external reader. The passive sensor uses two spiral coils to transduce pressure changes into resonant frequency shifts, while the external portable reader tracks the system's impedance and phase change.

What limitations of traditional ICP monitoring methods does the new wireless system aim to address?

The study highlights the limitations of traditional ICP monitoring methods, such as those using impedance analyzers or Vector Network Analyzers (VNAs), which are often heavy, expensive, and nonportable, limiting their use to laboratory settings. Also, grid dip oscillator technology faces constraints in application to ultrasmall sensors resonating at GHz frequencies, including limited sweeping frequency range and frequency drift issues. The new approach addresses these limitations with a portable and cost-effective solution.

What are the next steps in refining wireless ICP monitoring, and what potential impact could this technology have on neurological care in the future?

Future development will focus on optimizing the antenna size, adjusting power radiation, selecting an appropriate Analog-to-digital converter (ADC), and refining the signal processing algorithm. Integration into a helmet is also envisioned, potentially transforming neurological care by providing a safer, more convenient, and more effective means of monitoring brain pressure. These refinements could lead to widespread adoption of wireless ICP monitoring in clinical practice, improving outcomes for patients with hydrocephalus and other neurological conditions.

Digital illustration of a brain with wireless sensor networks, symbolizing wireless intracranial pressure monitoring.

Brain Pressure Monitoring: The Wireless Revolution in Healthcare

Elliot Brynn in Health & Wellness August 2025 • 4 min read.

"A new wireless sensor technology promises to transform intracranial pressure monitoring, offering safer and more convenient options for patients."

Hydrocephalus, a condition characterized by increased pressure within the brain due to fluid accumulation, affects a significant number of individuals, particularly newborns. This condition, more prevalent than well-known disorders like Down syndrome or deafness, is a leading cause of brain surgeries in children. Traditional methods of monitoring intracranial pressure (ICP) involve the use of catheters, which unfortunately carry risks such as infection, traumatic hemorrhage, and device malfunction. This has spurred interest in the development of wireless solutions for ICP monitoring to reduce these complications and improve patient care.

The concept of telemetric monitors for ICP monitoring first emerged in the 1990s, paving the way for fully implantable MEMs-based ICP sensors and portable readout monitors. These advancements aimed to provide continuous data collection via wireless communication. A wireless ICP sensor can be designed as either passive or active. While active sensors offer benefits such as longer communication distances and improved signal-to-noise ratio (SNR), they require a power supply, increasing their size and weight and necessitating periodic battery replacement. This limitation makes active sensors less suitable for long-term continuous monitoring. Therefore, passive resonant sensors, based on tank circuits, have gained traction due to their suitability for long-term implantation with minimal disturbance to surrounding tissues.

Recent developments in Micro-Electro-Mechanical Systems (MEMS) technology have facilitated the creation of ultrasmall passive resonant sensors that can be easily implanted into the human brain. These sensors measure pressure by detecting changes in the resonant frequency of a tank circuit. Some studies have reported ultrasmall sensors resonating at frequencies ranging from 350 MHz to 2.4 GHz. However, traditional methods of measuring ICP using impedance analyzers or Vector Network Analyzers (VNAs) are often heavy, expensive, and nonportable, limiting their use to laboratory settings. In contrast, grid dip oscillator technology, while offering similar telemetry devices, faces constraints in application to ultrasmall sensors resonating at GHz frequencies, including limited sweeping frequency range and frequency drift issues.

A Novel Approach to Wireless ICP Monitoring

Digital illustration of a brain with wireless sensor networks, symbolizing wireless intracranial pressure monitoring.

In a recent study published in IEEE Transactions on Biomedical Circuits and Systems, researchers Fa Wang, Xuan Zhang, Mehdi Shokoueinejad, Bermans J. Iskandar, Joshua E. Medow, and John G. Webster introduced a novel wireless intracranial pressure readout circuit designed for passive wireless LC sensors. Their system includes an implantable passive sensor and an external reader, offering a wide frequency range (35 MHz-2.7 GHz) and low-cost components. The passive sensor, composed of two spiral coils, transduces pressure changes into resonant frequency shifts, while the external portable reader tracks the system's impedance and phase change.

The proposed circuit topology offers several advantages, including simplicity, reliability, and suitability for medical practice. The prototype device achieves a measurement distance of over 2 cm, a sample frequency greater than 6 Hz, and fine resolution with good measurement accuracy. With a responsivity of 0.92 MHz/mmHg and a resolution of 0.028 mmHg, the system demonstrates promising performance for ICP monitoring. Additionally, COMSOL specific absorption rate simulation confirms the system's safety.

Considerations for improving the device include:

Optimizing the size of the antenna
Adjusting the power radiation
Selecting an appropriate Analog-to-digital converter (ADC)
Refining the signal processing algorithm

Traditional methods of ICP monitoring often rely on catheters linked to external sensors, increasing the risk of complications such as infection and hemorrhage. Wireless ICP sensors offer a less invasive alternative, reducing these risks and improving patient comfort. While active wireless sensors provide advantages like longer communication distances and better signal-to-noise ratios, they require a power supply, limiting their suitability for long-term continuous monitoring. The novel passive resonant sensor presented in this study addresses these limitations, offering a promising solution for continuous ICP monitoring with minimal disturbance to surrounding tissues.

Conclusion

The innovative wearable readout system presented in this study offers a promising solution for wireless continuous ICP monitoring. With its wide frequency range, fine resolution, and potential for integration into a helmet, this technology has the potential to transform neurological care by providing a safer, more convenient, and more effective means of monitoring brain pressure. Further refinements and optimizations could pave the way for widespread adoption of wireless ICP monitoring in clinical practice, improving outcomes for patients with hydrocephalus and other neurological conditions.