Hannah P. Palahnuk, Nicolas A. Tobin & Keefe B. Manning, Red Blood Cell Deformation at Supraphysiological Strain Rates Using a Droplet Framework. Ann Biomed Eng (2026).
https://doi.org/10.1007/s10439-026-04000-4
Pennsylvania State University – Collaboration with Goodfellow's Baltimore site, Potomac Photonics
Penn State University | Potomac Photonics (Acquired by Goodfellow) | Advanced Microfluidic Solutions | February 2026
Abstract
Hemolysis remains a critical limitation in mechanical circulatory support devices (MCSDs), yet red blood cell (RBC) deformation mechanics under supraphysiological strain rates remain inadequately characterized, constraining predictive capability for in silico optimization. Potomac Corporation fabricated a custom hyperbolic converging microchannel assembly for the Plane 2 extensional-flow configuration to ±5 μm dimensional tolerance, preserving a 0.150 mm constriction geometry and optical surface quality compatible with high-speed microscopy. The enclosed architecture necessitated split-body CNC processing, metrological control beyond nominal ±50 μm tolerance, vapor polishing with dimensional compensation, and controlled solvent bonding to maintain geometric fidelity and structural stability. The completed device satisfied the geometric specifications defined by Pennsylvania State University and was subsequently utilized in their independent investigation of RBC deformation under MCSD-relevant flow conditions.
Overview
At Goodfellow’s Baltimore site, Potomac Photonics fabricated a hyperbolic converging microchannel assembly using precision CNC machining, metrological control, vapour polishing, and solvent bonding to preserve ±5 μm dimensional tolerance and optical clarity within the designed architecture given by the Penn State University researchers.
Manufacturing Challenges & Engineering Solutions
1. Enclosed Channel Architecture
- Challenge: The enclosed internal geometry precludes single-pass subtractive machining. Optical transparency and ±5 μm dimensional tolerance requirements exceeded the capability of low-resolution additive fabrication.
- Solution: The device was partitioned into two independently machined halves, enabling controlled micro-CNC generation of each channel surface prior to bonded assembly of the hyperbolic contraction architecture.
2. Dimensional Tolerance
- Challenge: The specified ±5 μm tolerance exceeded nominal ±50 μm CNC capability, necessitating preservation of geometric fidelity across the full contraction profile.
- Solution: Tool-path optimization, enhanced metrological control, and iterative dimensional verification were implemented to maintain the defined tolerance envelope throughout the machining sequence.
3. Surface Finish & Constriction Integrity
- Challenge: CNC milling generated surface artefacts that degrade optical clarity. The 0.150 mm constriction geometry and limited bonding interface increased susceptibility to dimensional distortion, stress cracking, and deformation during assembly.
- Solution: Vapor polishing with dimensional compensation reduced machining artefacts while preserving channel height. Precision-aligned solvent bonding with uniform-pressure fixturing maintained geometric stability and structural integrity during final assembly.
Conclusion
Potomac Photonics fabricated the hyperbolic converging microchannel assembly in polymethyl methacrylate (PMMA) to ±5 μm dimensional tolerance, preserving the 0.150 mm constriction geometry and optical surface quality compatible with high-speed microscopy. The completed device satisfied the geometric requirements of the Plane 2 extensional-flow configuration and was supplied for use in the published investigation