FLUID Water Meter
I cofounded FLUID in 2015 with talented partners to build an IoT water monitoring platform for homeowners. Over three years, with support from investors who believed in our vision, I built everything from ultrasonic signal processing to cloud ML pipelines. We produced about 100 devices and learned invaluable lessons about bringing hardware to market. Residential water damage costs billions annually, but monitoring systems were expensive commercial products. We saw an opportunity for affordable clamp-on sensors—no plumber required.
The Journey
We started with an off-the-shelf ultrasonic meter to learn time-of-flight measurement. Our Kickstarter campaign brought in early supporters who helped fund custom clamp-on sensors with injection-molded enclosures. As the technical lead, I built most of the platform while managing contractors for PCB design, FPGA programming, and mechanical work. We progressed from 3D-printed prototypes to production units with proper tooling, built a calibration lab for training data, and shipped working devices. While we ultimately didn't reach the scale needed for sustainable manufacturing economics, we're proud of the complete IoT platform we built and grateful for the opportunity to tackle this challenge.
The Technical Challenge
Ultrasonic flow measurement is deceptively hard. Send sound waves upstream and downstream, measure the time difference, calculate flow. Simple in principle. Real-world conditions complicate everything. Transducer alignment matters—a few degrees off and readings fail. Temperature changes affect sound speed in water. Air bubbles scatter the signal. Partial pipe fill breaks the math. Crosstalk from solid-fluid interfaces adds noise. We needed reliability across pipe materials (copper, PVC, PEX), diameters (½-inch to 2-inch), varying flow rates, and environmental conditions—all on battery power with strict computational limits.
What We Built
Hardware: Clamp-on ultrasonic sensor, injection-molded enclosure, custom PCBs, FPGA signal processing, battery management
Firmware: C++ real-time signal processing, Kalman filtering, temperature compensation, low-power wireless
Calibration Lab: PLC-controlled water systems generating labeled datasets with known flow rates
Cloud: AWS IoT Core, Lambda, DynamoDB for telemetry processing and storage
ML: Anomaly detection for leaks, usage pattern classification, training on calibration data
Apps: Mobile (iOS/Android), web dashboard, fleet management, OTA firmware updates
Real-Time Flow Detection
5 minutes of ultrasonic data at 1Hz showing household usage: faucet at 30s, toilet flush at 90s, shower at 2.5min. Our signal processing extracted these patterns from noisy sensor data in real-time.
Engineering Deep Dive
Extracting accurate flow from noisy ultrasonic signals on constrained hardware was the core challenge. Kalman filtering estimated true flow by combining measurements over time. The filter maintains a state estimate and updates as readings arrive, weighing each by reliability. This handled air bubbles, turbulence, and temperature fluctuations. The algorithm ran on embedded hardware with milliwatt power budgets. Temperature compensation was critical—sound speed in water changes 0.17% per degree Celsius. We continuously adjusted timing calculations across basement to outdoor conditions.
Leak detection requires pattern recognition, not just flow measurement. We trained ML models on calibration lab data. PLC-automated valves created labeled datasets with known flow rates—ground truth for training and validation. Anomaly detection learned baseline usage per household, then flagged deviations. A running toilet shows sustained low flow. A pinhole leak creates constant baseline. Models distinguished these from legitimate use like filling bathtubs. Usage classification identified fixtures by signature. Showers: 2-3 GPM sustained. Toilets: sharp spike plus refill. Faucets: intermittent on-off. Irrigation: scheduled high flow. Cloud infrastructure ingested 1Hz telemetry, storing time-series and running batch ML jobs.
Can't touch deployed devices. Everything works remotely or not at all. OTA firmware updates became critical. We found bugs, optimized algorithms, added features—all requiring updates to devices in crawl spaces. The system needed to be bulletproof: interrupted updates can't brick devices, rollbacks must work, remote diagnostics essential. We built device provisioning, health telemetry (battery, signal strength, reliability), and remote configuration. AWS IoT Core handled MQTT messaging, shadow states, and job management. Lambda processed data streams, DynamoDB stored device states.
Manufacturing & Hardware
Hardware has fundamentally different economics than software. Injection molding tooling costs tens of thousands before making a single part. Kickstarter funded initial tooling, but bridging prototype to production requires massive capital. Economics work at volume—but reaching volume needs upfront capital. MOQs dominate decisions. PCB manufacturers want 1,000+ boards. Injection molding becomes viable around 5,000+ units. Component suppliers have MOQs. You're negotiating batch sizes against unit economics against cash flow. Managing contractors across mechanical, electrical, and firmware requires tight integration. An enclosure change affects PCB mounting. Firmware optimization might enable smaller batteries, changing mechanical design. We produced 100 devices—enough to validate technology, nowhere near sustainable economics.
From Prototype to Production
Three years from concept to production: off-the-shelf validation, 3D-printed iteration, injection-molded manufacturing.
Off-the-Shelf Sensor
Commercial ultrasonic meter to validate concept and learn time-of-flight fundamentals.
Kickstarter & 3D Prints
Kickstarter for custom sensor development. Rapid iteration with 3D-printed enclosures. Built calibration lab.
Injection-Molded Units
~100 devices with injection-molded enclosures, custom PCBs, FPGA processing. Full cloud platform, mobile apps, ML analytics deployed.
The Scaling Challenge
Hardware startups face a fundamentally different challenge than software. While we succeeded technically—building working sensors, reliable firmware, and scalable cloud infrastructure—we learned that hardware economics require a different playbook. Tooling, inventory, assembly, testing, and regulatory compliance all demand significant capital before generating revenue. To reach the volumes where unit economics become sustainable, you need either substantial investment or enough pre-orders to fund manufacturing directly. Despite the support of investors who believed in our vision and customers who backed us on Kickstarter, we didn't reach the scale needed to bridge that gap. The classic challenge: you need volume for viable unit costs, but you need capital to reach volume. Our 100 devices validated the technology, but sustainable manufacturing required thousands. We're grateful to everyone who supported us on this journey—our investors who took a chance on the vision, our Kickstarter backers who believed early, and our team who worked incredibly hard to bring this to life. The experience taught us that in hardware, technical excellence is necessary but not sufficient.
What I Learned
Ultrasonic Tech: Signal processing is as hard as the physics. Kalman filtering essential but required extensive calibration. Temperature compensation mattered more than expected. Real-world messier than lab.
Machine Learning: Labeled data harder than models. Calibration lab was critical. Usage patterns more diverse than anticipated. Anomaly detection requires understanding 'normal'—which varies by household.
Manufacturing: Tooling and MOQs dominate unit economics. Prototype-to-production gap is enormous. Design for manufacturing isn't added later. Managing contractors across disciplines requires tight integration.
Startup Economics: Technical risk differs from business risk. We reduced technical risk substantially, but business risk remained. Hardware needs different capital structures than software.
Solo Engineering: One person can build remarkable systems by managing scope and delegating specialized work. Full-stack means knowing enough about each layer to make good decisions, not being expert at everything.
FLUID taught me more than any project before or since. We built technology that worked, learned deeply across domains from ultrasonic physics to ML to manufacturing economics, and had the privilege of working with talented cofounders, supportive investors, and early believers who took a chance on our vision. The experience shaped my approach to production systems. Shipping matters more than perfection. Real-world conditions humble lab results. OTA infrastructure isn't optional for IoT. Business viability requires more than technical excellence. Three years, 100 devices, countless lessons. I'm grateful for the opportunity to have tackled this challenge and for everyone who made it possible.