Dripito — IV Drip Flow Monitor (Rev-B)

Improving a low-cost intravenous infusion flow-rate monitoring device for paediatric care in humanitarian healthcare settings. ETH Zürich, Global Health Engineering — semester project, 2026.

A single-AA-cell IV drip monitor for resource-constrained clinical environments. Custom STM32G0 PCB, optical dual-beam drop detection, monochrome graphic LCD, piezo alarm, ASA-printed enclosure with gear-driven broom-holder chamber clamp.

→ Full project page: gluflex.github.io/dripito

Interactive dual-beam simulation, clickable PCB architecture, validation results, architecture decisions, assembly guide. This README covers only the essentials for cloning, building, and reproducing.

At a glance

MCU	STM32G071C8TX
Hardware	Rev-B PCB, KiCad 8.x, hand-assembled
Detection	Dual-beam optical, sphere-model volume calibration
Power	Single AA Li-ion via FFC, TPS610981 boost converter
Enclosure	ASA white FDM, sliding-gear chamber holder — Rev-B integrates the assembly for testing; full mechanical rework expected for Rev-C
Validation	19 gravimetric-paired bench runs across 3 sessions (5 V_50 calibration + 11 position-drift + 3 raw-waveform-paired), macro-20 drip set; 7 raw-waveform captures total (4 unpaired warm-ups)
BOM	~CHF 39, single-qty (see project page)
Submission	2026-05-14

Reproduce the analysis

One command, on a clean machine with Docker:

cd analysis/
docker compose up regenerate-figures-sample   # cold-clone test (sample data)
docker compose up regenerate-figures          # real campaign data

Pipeline source: analysis/notebooks/validation.ipynb. Dependencies hash-locked in analysis/requirements.txt. Protocol: docs/testing-and-validation.md.

Build the firmware

1. Open firmware/STM32CubeIDE/Dripito/ in STM32CubeIDE.
2. Project → Build All.
3. Connect ST-Link, Run → Debug.

Pin maps in firmware/README.md.

Hardware fabrication

PCB from hardware/gerbers/ (JLCPCB / PCBWay).

Enclosure: STEP and STL exports in hardware/3dmodels/Enclosure/ (source CAD in Onshape). The current Rev-B enclosure is not the final mechanical design — it integrates the PCB + chamber holder + optics + battery into a testable assembly so the rest of the device can be validated. A full mechanical rework is expected for Rev-C. See docs/decisions/chamber-holder-mechanism.md, docs/decisions/sensor-arm-alignment.md, and docs/enclosure-requirements.md for the rationale and Rev-C path.

Repository layout

hardware/        KiCad 8.x project — schematic, PCB, libs, datasheets, gerbers, 3D models (PCB + Enclosure)
firmware/        STM32CubeIDE workspace (Dripito Rev-B)
enclosure/       Rev-B-is-not-final framing + cross-references; CAD lives in hardware/3dmodels/Enclosure/
docs/            Architecture decisions, requirements, results, limitations
data/            Raw validation CSVs, UART logs, gravimetric scale streams, geometry, edge cases
analysis/        Reproducible analysis pipeline (Docker + Jupyter) + diagnostic plotters + figures
tools/           Bench helpers (UART logging, scale logging, position-overlay rendering)
site/            GitHub Pages source (Astro)
media/           Photos, renders, demo clips
HANDOVER.md      State-of-the-prototype handover (Rev-B → Rev-C, what works / blockers / path)
CONTRIBUTING.md  Contribution guidelines (PRs paused during grading)

Each folder has its own README.md.

For the next person picking this up, start with HANDOVER.md: what works in Rev-B scope, the three blockers (position-dependence, drop-shape oscillation, tilt sensitivity), and the Rev-C optical-front-end path. docs/limitations.md §17 is the matching architectural finding with bench evidence.

Citation

A bachelor thesis preceded this work:

Catarci, L. (2025). Improving a Low-Cost Intravenous Infusion Flow-Rate Monitoring Device for Paediatric Care in Humanitarian Healthcare Settings. ETH Zürich, Global Health Engineering. DOI: 10.5281/zenodo.16902366.

The Rev-B work in this repository:

Catarci, L. (2026). Dripito — Open-Source IV Drip Flow Monitor (Rev-B). ETH Zürich, Global Health Engineering. DOI: 10.5281/zenodo.20199232.

License

• Code, firmware, docs, data: CC BY 4.0
• Hardware (KiCad project, custom symbols, most footprints): CERN OHL 2.0 Permissive
• Three specific custom footprints: CC BY-SA 4.0 — see hardware/IV_Flow_Monitor_Footprints.pretty/README.md
• CubeMX/HAL files retain Copyright (c) STMicroelectronics headers.

Author and supervision

Leandro Catarci — MSc Mechanical Engineering, ETH Zürich. Semester project at ETH Global Health Engineering, 2026.

Jakub Tkaczuk — Supervisor. Prof. Elizabeth Tilley — Group head, Chair of Global Health Engineering, ETH Zürich.

Project originator: Dr. Michelle Niescierenko — Boston Children's Hospital / Harvard Humanitarian Initiative. Clinical collaborator: Dr. Janis Tupesis — University of Wisconsin / WHO Emergency Medical Teams.