Project
| # | Title | Team Members | TA | Documents | Sponsor |
|---|---|---|---|---|---|
| 66 | A New Approach to an External Ventricular Drain (Capstone Project) |
David Kapelyan Isiah Lashley Ralph Nathan |
Jason Jung | design_document1.pdf final_paper1.pdf grading_sheet1.pdf proposal1.pdf video |
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| Team Members: - Ralph Nathan (ralphn2) - David Kapelyan (davidik2) - Isiah Lashley (ilashl2) # Problem External Ventricular Drains (EVDs) are used to drain cerebrospinal fluid (CSF), but if done incorrectly, they can cause severe damage, including death. To ensure the correct amount of CSF is drained, the pressure transducers on the EVD must be properly zeroed. However, patients often move during sleep or daily activities such as showering, which can lead to incorrect pressure readings and improper CSF drainage. According to Dr. Suguna Pappu, there have been numerous cases where approximately 40 ccs of CSF were drained instead of the intended 10 due to zeroing errors. This, again, can result in significant harm or even death. In summary, a new approach to EVDs is necessary, one that provides stable pressure readings even when the patient is in motion. This capstone project aims to create advancements in EVDs. # Solution We plan to utilize an STM32 microcontroller to process input from a pressure transducer connected to the catheter through which cerebrospinal fluid (CSF) is drained from the brain. Our design will incorporate a pipe tee in series with a two-way solenoid valve. The catheter extending from the skull will be connected to the tee, which will also be fitted with a pressure gauge. This pressure gauge will be linked to the microcontroller, which will control whether the solenoid valve is open or closed. Measuring pressure digitally, rather than using a manometer, will eliminate the issue of set-point shifts caused by patient movement. Additionally, there will be no need to manually set a “zero” point, as this can be calibrated in software. We will use an instrumentation amplifier with a shunt resistor to buffer signals from the pressure transducer, ensuring accurate readings by the microcontroller. Digital signal processing (DSP) will then be performed via the microcontroller, including noise filtering, adaptive thresholding for real-time pressure management, and data logging of pressure readings. The system will regulate the flow of CSF to a drain collection bag via a push-connected solenoid valve. The microcontroller will communicate with a display or bedside monitor via Bluetooth, presenting pressure data—including real-time pressure graphs, an alarm system for abnormal pressure readings, and data logs for physician review—through a graphical user interface (GUI). Additionally, we will implement fail-safes to prevent over-drainage or blockage and include a manual override in case of system failure. # Solution Components ## STM32 Microcontroller An STM32 microcontroller with an on-package RF transceiver that supports Bluetooth will be utilized. The ADC of the controller supports a resolution of 12 bits which will be useful for accurately measuring the output signal of our pressure gauge. The STM32 Microcontroller comes with an internal reference voltage that is typically derived from the supply voltage. ## Power System Circuit A high-voltage rail powered by an AC-DC wall adapter will be used to power the board. A linear regulator will be utilized to decrease the voltage such that it can be used to power the microcontroller. ## Push Connect Solenoid Valve For Drainage A switch will be placed between the high-voltage rail and the solenoid input. The switch will be controlled by an output signal from the microcontroller. ## Pressure Transducer The pressure transducer will be connected to the pipe tee. The pressure transducer will need to be a precision pressure transducer as the standard Intracranial Pressure is approximately 16mg(0.309 PSI) which is a relatively low pressure. The transducer will have a current output which will be connected to a shunt resistor across which the voltage will be measured using an instrumentation amplifier. # Criterion For Success A successful project will result in a device that accurately reads and processes pressure data from a transducer with minimal noise and high precision. The system must effectively regulate cerebrospinal fluid (CSF) drainage by dynamically controlling a solenoid valve to maintain an average outflow of 10cc/hour, preventing over-drainage or blockage. Additionally, the microcontroller must wirelessly transmit real-time pressure readings via Bluetooth to a bedside monitor, where a graphical user interface (GUI) will display real-time pressure graphs, generate alarm notifications for abnormal pressure levels, and log data for physician review. To ensure safety and reliability, the system must incorporate fail-safes to prevent malfunctions and provide a manual override for emergency control. By meeting these criteria, the project will achieve its goal of delivering an automated, accurate, and user-friendly solution for CSF drainage management. # Parts: STM32 PCB Push Connect Solenoid Valve Pipe Tee Pressure Transducer Instrumentation Amplifier Links: ¼” push connect solenoid valve ⅛” npt solenoid valve https://www.omega.com/en-us/pressure-measurement/pressure-transducers/px119/p/PX119-015GI https://www.coleparmer.com/i/cole-parmer-0-25-accuracy-transmitter-0-to-2-psi-4-to-20-ma-output/6807503 https://www.mouser.com/ProductDetail/Analog-Devices/ADR435BRZ?qs=WIvQP4zGanhj7%2FQWeFYslw%3D%3D&utm_id=22030944703&gad_source=1&gclid=CjwKCAiAtYy9BhBcEiwANWQQLyuDFchHNWjCoLscoWoVpM2fdflY2CcCi-fQ9bxPrEm5EPQFvoIeNxoCPqgQAvD_BwE |
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