Cerebrospinal Fluid Pump

The goal of the project is to design, test and refine a compact, low-cost, oscillatory-flow pump that will reproduce realistic cerebrospinal fluid (CSF) flow conditions within a given range of human/animal cerebrospinal models. Flow rates mimic cardiac and respiratory frequencies and have an adjustable frequency and flow volume.

Background


Central nervous  system  (CNS)  diseases can be  difficult to  treat  because  many potential drugs cannot reach the brain due to the blood brain barrier. A potential new route to get drugs to the  brain is to  inject  them  into  the  cerebrospinal  fluid  (CSF). One way to  bypass  the blood brain barrier is by direct injection of drugs to the CSF. Drugs can then spread/mix in the CSF and be distributed directly to the brain and spinal cord tissue surface.

The CSF is a  clear  water-like fluid  located  around  the  entire brain and spinal cord and pulses each time the heart beats thereby making it a good medium to transport drugs to the  CNS. One problem with delivering drugs to the CNS by the CSF is that it requires extremely expensive (and ethically nebulous) animal studies to understand and optimize the delivery device and  protocol. Thus, the NIML is designing the world's first laboratory bench-top simulator of the complete CSF system for brain therapeutic development. They have an ongoing project to make a detailed in vitro model that accurately represents the CSF anatomy and flow that would accommodate testing with medical devices. The Cerebrospinal Fluid Pump project is designed to pair with the NIML's existing human spinal model to make a complete CSF system simulation.

Oscillatory Flow
By definition flow of fluid, gas, or electricity moves along or out steadily and continuously in a current or stream and oscillation is the repetitive variation, typically in time, of some measure about an equilibrium. Together, oscillatory flow is the variation of a wave frequency in time. The oscillatory waveform chosen to mimic the same frequency of a heat beat takes the form of a sinusoidal wave. Typically, a resting healthy human heat beat can range anywhere from 60 to 100 beats per minute (bpm). The use of fluid dynamics can assist in predicting the behaviors of flow in a pump in multiple ways. With a known frequency or speed of a fluid, displacement or stroke volume, and the area of the cylinder that the fluid is passing though, then the continuity equation can be used as a way to model fluid flow. Another basic equation that can be used to predict other aspects of fluid flow such as pressure is Bernoulli’s Equation.

=Deliverables=

The cerebrospinal-fluid pump must produce an oscillating flow within spinal cord models ranging from the size of a human to a small vertebrate. This flow must be adjustable in volume and frequency. Ideally the design should be low-cost and easy to operate, as it is intended to be widely distributed for laboratory testing. The design must also include a 5V, square wave-form trigger that simulates the human heartbeat in MRI testing.

=Specifications=



=Design Concepts= {| class="wikitable"

Belt Design
Features:
 * Belt driven by 2 stepper motors.
 * Dowel rod slider connected to belt and syringe to guide linear motion.

Pros:

Cons:







Flywheel Design

 * Single stepper motor drive
 * Adjustable flow volume
 * Lead screw adjustment for eccentricity offset
 * Interchangeable syringe mount
 * Light weight and Compact
 * single motor
 * Total length &asymp; 2inches more than syringe length
 * Frequency adjustable through computer Control
 * Frequency adjustable through computer Control


 * Pros
 * Frequency computer controlled
 * Robust/Repeat-ability
 * Easily convertable to non-ferrous materials
 * Simple integration for a pneumatic motor control


 * Cons
 * Manual volume control

Linear Actuator
Features:
 * Servo-motor linear actuator with relay.
 * programmable linear motion.

Pros:

Cons:
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=Problem Definition=

Specifications
=Team Members=