openUC2 microfluidics

Parametric microfluidic chips for openUC2 microscopes. Each chip is built by a Python script as native Autodesk Inventor parts (.ipt) and an assembly (.iam). The script talks to Inventor over COM (pywin32, the PyInventor toolchain). Every dimension ends up as an Inventor user parameter, and the script also exports STEP and print-ready STL files.

chip	folder
Leaf chamber	chips/leaf_chamber	slide-format perfusion chamber for a leaf sample: screw plug with O-ring (optional window), luer-lock inlet, luer (B, default) or reservoir (A) outlet, glued bottom coverslip

Layout

mfcad/                      shared library
  params.py                 parameter tables: base values + derived expressions, valid both in
                            Python (checks, initial geometry) and as Inventor expressions
  native_part.py            NativePart: sketches dimensioned against parameter expressions,
                            extrudes, coils (threads, lugs), patterns, fillets, chamfers,
                            health report, AP214 STEP and STL export, reading parameters back
  stock_parts.py            bought glass parts that openUC2-CAD-new lacks (coverslips)
  inventor_helpers.py       the shared openUC2 builder helper (session, CAD-new lookup, Builder) -
                            identical copy of openuc2-opmsimulator / openuc2-openraman, keep in sync
chips/<chip>/
  <chip>.py                 parameters, variants, design checks (plain Python)
  build_<chip>.py           Inventor builder: parts, assembly, interference check, STEP/STL
  check_<chip>.py           independent checks on the STEP exports + figures for docs/
  INVENTOR/                 generated .ipt/.iam/.stp/.stl and "<part> - params.json"
  docs/                     figures

Environments

• Inventor builds: C:\Users\benir\miniforge3\envs\pyinventor\python.exe with Inventor 2025 running. The session helper restores SilentOperation and closes only the documents the script opened.
• Checks and figures: uv run --with cadquery --with trimesh --with rtree --with scipy --with shapely --with networkx --with matplotlib python check_<chip>.py.
• Parameter tables and design checks: any Python 3.10+ (python <chip>.py).

Adding a chip

1. Copy chips/leaf_chamber to chips/<new_chip> and rename the three scripts.
2. In <chip>.py, declare the knobs with P(name, value, unit, comment) and the derived values with D(name, "expression", ...). Write expressions as plain arithmetic of parameter names, with units on literal numbers (0.3 mm). Write the design checks.
3. In build_<chip>.py, describe the features with NativePart, always in parameter expressions: part.circle(s, "-out_x", 0, "res_d", ...), part.extrude(s, "res_top - res_floor", kNeg, kCut, ...). Parameters are created in the part on first use, so each part carries only what it needs.
4. Names follow openUC2-CAD-new (PRT - 9xxx - <ABBREV> - V04 - <variant>, BUY - ...). Use CAD-new parts where they exist; the O-rings come from STD/ISO 3601-1 - O-rings. Provisional numbers: 9300–9302 are taken by the leaf chamber.

Frame convention used so far: z = 0 on the glue plane (top of the bottom coverslip = sample plane), chamber centre at the origin, inlet towards +X.