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Design only · h.r.3.3 PDK

Calcium Urinalysis Chip

calcium

Urinary calcium assay chip.

H.R.3.3 design, made by the design software

Designed by Erica Francis · Gale Lab, University of Utah

Calcium Urinalysis Chip. A computer render of the design, not a photograph: its body drawn see-through, its channels in orange. The chip is 19.4 mm × 12.2 mm × 3.8 mm. Beside it, its cross-section across the middle.
Rendered from its design files, not photographed: the body see-through, the channels orange, and its cross-section beside it. Pictures in one family share one scale.

Geometry

Top view of the Calcium Urinalysis Chip, generated from OpenSCAD source Isometric view of the Calcium Urinalysis Chip, generated from OpenSCAD source

Top view (left) and isometric view (right) of the placed-and-routed chip. Rendered with OpenSCAD from the chip’s SCAD source, calcium_reroute.scad. Click for high-resolution.

Download: PNG (top) · PNG (iso) · SCAD source ↓

Specifications

Inputs
3 (soln1, soln2, soln3)
Outputs
1 (out)
Mixers
2 × diffmix_25px_0
Serpentine channels
3 (p_serpentine_0 × 2, _3 — see pcell manifest)
Substrate
2550 × 1600 × 230 (h.r.3.3 PDK)
Standard cells
diffmix_25px_0, p_serpentine
Status
H.R.3.3 design, made by the design software

Assay

This chip is designed to measure urinary calcium concentration via the Arsenazo III colorimetric reaction. Arsenazo III dye binds Ca2+ in acidic conditions to form a purple/violet complex whose absorbance (typically read at 650 nm) is proportional to the calcium concentration in the original sample.

Clinically, urinary calcium quantification supports kidney stone risk screening and mineral metabolism studies. The Arsenazo III chemistry is the same assay characterised in Tazin et al. 2022, and the chemistry of the calcium-quantification case study in Goenner et al. 2025, after which the related smart_toilet chip is named.

The chemistry is adapted from the Beckman Coulter AU480 reagent kit BASOSR6x117 (Calcium). The chip combines the urine sample with two reagent streams at the volumetric ratios required by the Arsenazo III protocol; the output channel collects the mixed product for off-chip spectrophotometric readout.

Files

calcium_reroute.scad is the placed-and-routed 3D geometry — the main OpenSCAD source for this chip. h.r.3.3_calcium_pcells.lef contains chip-specific cell abstracts. pcell_out_scad lists the parametric serpentine-channel variants this chip required (with L1 / L2 / turn count). The PNG renders are high-resolution versions of the views shown in the Geometry section above.

Papers

  • Related methodology archetype

    Goenner, B., Temple, S., Zapata, S., Wakeham, D., Snelgrove, A., Gaillardon, P.-E., Nordin, G. P., & Gale, B. K. (2025). An open source platform to automate the design, verification, and manufacture of 3D printed microfluidic devices. Scientific Reports, 15, 33077. DOI: 10.1038/s41598-025-15976-9

Applications

For research use only. Not for use in diagnostic procedures.

A design for urinary calcium quantification by the Arsenazo III colorimetric method, the chemistry characterised in Tazin et al. 2022 and used in the calcium case study of Goenner et al. 2025. Such assays support kidney stone risk screening and mineral metabolism studies. One of the urinalysis chip designs in the Gale Lab urinalysis chip family (Erica Francis).

Tags

  • chip
  • demo
  • discrete-microfluidics
  • h.r.3.3
  • urinalysis
  • calcium-assay
  • arsenazo-iii
  • spectrophotometric
  • passive-metering
  • multi-input

Citation & license

Erica Francis, Gale Lab, University of Utah

See the Papers section above for the related methodology archetype citation.

Design files from the public openmfda_flow repository (utah-MFDA), commit cc5dfc5 of 29 May 2026, on its urinalysis_suite_automation branch.

License: MIT (Copyright (c) 2021 utah-MFDA; Copyright (c) 2026 Gale Lab, University of Utah).