Non-Surgical, In-Stent Membrane Bioelectronics for Long-Term Intracranial Pressure Monitoring

Introduction: : Accurate and continuous intracranial pressure (ICP) monitoring is critical for diagnosing and managing traumatic brain injury, hydrocephalus, and idiopathic intracranial hypertension. Traditional gold-standard techniques, such as intraventricular catheters, require cranial penetration, carrying significant risks including hemorrhage, infection (up to 25%), and sensor drift, thus limiting their suitability for long-term outpatient monitoring. [1] Emerging wireless telemetry approaches offer reduced invasiveness but are hindered by signal attenuation through biological tissue and dependency on close-proximity readers. [2] To address these limitations, we developed a novel non-surgical, in-stent membrane bioelectronic system integrating an ultra-thin capacitive membrane sensor onto a commercial stent platform. The sensor is capable of detecting subtle pressure changes within the dural venous sinus (DVS) without skull penetration, providing a minimally invasive, stable, and long-term solution for ICP monitoring. Our system utilizes a fully insulated guidewire to transmit real-time pressure signals externally through the antecubital vein, ensuring drift-free performance and eliminating the need for wireless implants near brain tissues. In vitro and in vivo studies validate the superior sensitivity (0.052%/mmHg), wide dynamic range (3-30 mmHg), rapid response time ( < 0.2 s), and remarkable long-term stability with less than 0.1% drift after 30 days. Statistical analysis demonstrated excellent agreement with clinical reference devices. These findings suggest that our platform represents a transformative shift in ICP monitoring, with potential applications extending from intensive care to outpatient neurocritical care. [3]

Materials and

Methods: : The core sensing element is a flexible, capacitive membrane sensor composed of micropyramidal, porous polydimethylsiloxane (PDMS) sandwiched between gold electrodes, optimized to enhance sensitivity and mechanical durability. The membrane structure was fabricated using electroforming and a solution-evaporation process to introduce porosity, enabling superior deformation and capacitance modulation under low-pressure stimuli. The sensor dimensions were miniaturized (300 µm thickness, 0.4 mm width, 6 mm length) to ensure safe delivery via a 4.2-Fr Fubuki guide catheter and seamless deployment into the DVS. A parylene C coating was applied for biocompatibility and insulation. In vitro validation employed a custom-built cranial phantom replicating pulsatile venous flow, where the sensor capacitance changes were correlated with reference pressure sensors under pressures ranging from 3-30 mmHg. Dynamic testing evaluated response/recovery times, repeatability over 50,000 loading cycles, and durability under mechanical bending. In vivo evaluation was performed in a swine model by deploying the sensor-stent system via femoral vein access into the transverse sinus. Intracranial pressure variations were artificially induced using a subdural balloon catheter, and the resulting sensor data were benchmarked against a commercial microcatheter and Codman systems. High-frequency capacitance data were captured and analyzed via LabVIEW interfacing with LCR meters. Spearman correlation analysis, Bland-Altman plots, and intraclass correlation coefficients quantified the accuracy of the device relative to clinical standards. Post-explant analyses including microstructural imaging and long-term stability testing were conducted to assess device integrity after 30 days.

Results, Conclusions, and Discussions:: The in-stent membrane bioelectronic system successfully enabled real-time, continuous ICP monitoring without skull penetration. In vitro tests confirmed excellent linearity (R² > 0.99) across 3–30 mmHg, fast response and recovery ( < 0.2 s), and robust durability with over 50,000 cyclic loadings showing no performance degradation. Comparative analysis revealed that porous micropyramidal PDMS structures significantly enhanced sensor sensitivity (0.052%/mmHg) compared to non-porous counterparts. The sensor-stent platform maintained stable positioning and seamless functionality during in vivo deployment in swine models, where the device accurately tracked ICP variations induced by a subdural balloon catheter. Data from the thin-film sensor exhibited a Spearman correlation coefficient of r = 0.906 with clinical reference devices, minimal bias (−0.17 mmHg), and consistency within error guidelines ( < 2 mmHg for 0–20 mmHg range). Notably, the sensor’s drift was negligible ( < 0.1%) even after 30 days post-implantation, and microstructural analysis revealed minor dielectric wear offset by compensatory micropore formation without functional loss. The platform also demonstrated higher sampling frequency, improved continuity in dynamic ICP tracking, and greater stability than traditional microcatheter systems, which often failed to maintain consistent positioning within the transverse sinus. Importantly, the system’s wired design through the antecubital vein eliminated complications associated with wireless telemetry, such as tissue signal attenuation. Overall, this work introduces a transformative bioelectronic platform for safer, long-term ICP monitoring, offering significant advantages in sensitivity, invasiveness, sampling rate, and drift stability over existing methods. The miniaturized design, compatibility with standard catheter delivery systems, and capability for outpatient monitoring position this technology as a promising candidate to revolutionize neurocritical care management. Future research will focus on wireless data acquisition modules, chronic implantation studies, and extension of the platform to monitor other organ compartments affected by pressure dysregulation.
[1] S. Qvarlander et al., J. Appl. Physiol. 2013, 115, 1474.
[2] R. Herbert et al., Nano Today 2022, 46, 101557
[3] J. Lee et al., Adv. Healthcare Mater. 2025, 2404680

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