Research ArticleBiosensors

Epidermal electronics for noninvasive, wireless, quantitative assessment of ventricular shunt function in patients with hydrocephalus

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Science Translational Medicine  31 Oct 2018:
Vol. 10, Issue 465, eaat8437
DOI: 10.1126/scitranslmed.aat8437

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Sensors for shunts

Ventricular catheters (shunts) relieve pressure on the brain by rerouting excess cerebrospinal fluid that accumulates in patients with hydrocephalus. Catheter occlusion or malfunction can be difficult to diagnose without medical imaging or surgery. Here, Krishnan et al. fabricated thin, flexible, epidermally adherent sensors to monitor subdermal shunt function. In five subjects with hydrocephalus, the sensors could detect direction-dependent heat transport associated with fluid flow at skin sites over the catheter versus skin adjacent to the catheter. The sensors detected shunt malfunctions in some patients that were confirmed by imaging or surgery. With wireless data transfer capabilities, these flexible sensors offer a noninvasive way to monitor shunt function.

Abstract

Hydrocephalus is a common and costly neurological condition caused by the overproduction and/or impaired resorption of cerebrospinal fluid (CSF). The current standard of care, ventricular catheters (shunts), is prone to failure, which can result in nonspecific symptoms such as headaches, dizziness, and nausea. Current diagnostic tools for shunt failure such as computed tomography (CT), magnetic resonance imaging (MRI), radionuclide shunt patency studies (RSPSs), and ice pack–mediated thermodilution have disadvantages including high cost, poor accuracy, inconvenience, and safety concerns. Here, we developed and tested a noninvasive, skin-mounted, wearable measurement platform that incorporates arrays of thermal sensors and actuators for precise, continuous, or intermittent measurements of flow through subdermal shunts, without the drawbacks of other methods. Systematic theoretical and experimental benchtop studies demonstrate high performance across a range of practical operating conditions. Advanced electronics designs serve as the basis of a wireless embodiment for continuous monitoring based on rechargeable batteries and data transmission using Bluetooth protocols. Clinical studies involving five patients validate the sensor’s ability to detect the presence of CSF flow (P = 0.012) and further distinguish between baseline flow, diminished flow, and distal shunt failure. Last, we demonstrate processing algorithms to translate measured data into quantitative flow rate. The sensor designs, fabrication schemes, wireless architectures, and patient trials reported here represent an advance in hydrocephalus diagnostics with ability to visualize flow in a simple, user-friendly mode, accessible to the physician and patient alike.

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