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Medical Background
Pulmonary Arterial Hypertension (PAH) is a medical condition characterized by higher than nominal blood pressure specifically caused the by deformities in the arteries of the lungs. Infants and children with a congenital heart defects are at a higher risk of developing PAH which can lead to heart failure and a shortened life span.
“Pulmonary Arterial Hypertension - Causes and Symptoms: Parkway East Hospital.” Parkway East Hospital, www.parkwayeast.com.sg/conditions-diseases/pulmonary-arterial-hypertension/symptoms-causes. Accessed 7 June 2024.
The Experimental Biofluidics Lab at UCSD, led by our sponsor Professor Geno Pawlak, is studying the genetic expression of cells that undergo three biomechanical stresses (pressure, shear stress, and cyclical stretching) for the purpose of developing pharmaceuticals that can help manage PAH.
1D uniaxial automated cell stretching system, cellmechanics.de
More on Cell Stretchers
More on Cell Stretchers
Cell stretchers are devices that replicate natural biomechanical forces and flows on mammalian cells, mimicking movements like heartbeats, breathing, and muscle contractions. With this technology, we can examine how cells respond to these biological processes in real time.
Improvement on Previous Work
Improvement on Previous Work
Previous iterations of cell stretchers have been developed by research teams. Where these designs have left room for improvement is in the combination of each of the 3 forces mentioned previously. No existing cell stretcher was able to induce conditions where all 3 of the desired parameters could be prescribed. The combination of stretching and shear stress was particularly important, made difficult by the need to enclose the cell membrane in a chamber of flowing fluid. Moving parts are a potential source of contamination, and they also disrupt flows characterized by a low Reynolds number when introduced improperly.
The teams’ final design was inspired by a previous model developed under the supervision of the Pawlak research group. This version was able to introduce pressure and shear stress, but was unable to incorporate cell stretching. The device was sealed with 26 sets of wingnuts, bolts, and washers. This required a significant time investment when initiating trials, and the uneven forces applied to the stretcher eventually led to deformations which compromised the seal. The device also left room for improvement in the measurement of flow. Dr. Pawlak wanted to avoid needing to rely on image processing to analyze the flow.
Design Objective & Requirements
Our primary objective was to create a device that applies pressure, shear stress, and cyclical stretching to cells. While devices that can apply shear stress and cyclical stretching individually do currently exist in research, there are no designs that has the ability to exert all three of these forces.
Functional Requirements:
Achieve Hele-Shaw flow
Hold 1 Hele-Shaw cell
Fit inside of incubator dimensions: 469.9 mm x 469.9 mm x 304.8 mm (18.5’x18.5’x12’)
Materials are medical grade, biocompatible, and temperature resistant to human body conditions of 37 oC
Hold pressure and remain sealed (no leakage)
Apply normal, shear stress, and cyclic stretching to cells that can be verified
Data acquisition of pressure, flow rate, and stretching throughout the experiments
Allows the users to visibly inspect the flow at any time throughout the experiment
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