Invisense2017 - 2019

Invisense

Advanced Humidity Monitoring System

Construction / IoT / Hardware

Handheld Invisense reader held against a tiled wall over an embedded sensor inlay

Invisense measures moisture inside building structures without opening them up. The sensor is a passive thin-film inlay cast into the structure; a handheld reader takes the measurement straight through the wall. I wrote the firmware and the measurement algorithm, built the app, and took the radio through CE certification.

Nothing in the wall has a battery

The sensor is a printed inlay (a spiral antenna coil and a pair of metallised pads on a flexible film) sealed into the structure with no power source and no radio of its own. All the electronics live in the handheld reader, which is held against the wall and takes the measurement through the material in between. Nothing has to be opened up to get a reading, and nothing buried in the building can go flat.

Flexible printed Invisense sensor inlays, each a spiral antenna coil on film

Which means someone has to stand in the right spot

A reading only happens where the reader can reach, so this is a measurement taken on site, with the unit held against the wall. Once the structure is closed, the inlay is invisible. Finding one is a drawing exercise: the sensor positions are specified in the building plans, and the reader goes where the plans say.

Three handheld Invisense readers showing the bilingual measurement UI

The algorithm and the app were developed together

A cross-platform React Native application for Android and iOS handling monitoring and data visualisation, developed in step with the measurement algorithm itself, because what the algorithm can honestly report and what the app should show a builder standing in a basement are the same design question.

Invisense Mobile Application Development

Radio certification is a process, and someone has to be in the room

The BLE design was chip-down rather than a pre-certified module, so there was no module certification to inherit and the product needed a full radio sweep: an anechoic chamber, a biconical antenna and a turntable, not a paperwork exercise. I led it, as liaison and on-site representative throughout. Being in the room is most of the job: the lab finds something, and you change the firmware that afternoon.

Scope: CE: EMC and radio
Design: Chip-down, full sweep

Then the same person flashes them

Assembly, firmware flashing and QA of 50+ units, done hands-on rather than handed to someone else, plus hardware design advisory and on-site troubleshooting when the boards did not behave the way the schematic promised.

What I owned

Firmware & Application Developer

Developed embedded firmware in C with FreeRTOS
Built React Native app for Android & iOS
Managed hardware QA and factory assembly processes
Led CE certification including wireless radio compliance
Provided hardware design advisory and onsite troubleshooting

Embedded C / FreeRTOS / React Native / Hardware QA / CE Certification / IoT

Gallery

All projects

50+ stations delivered

Mud Masters

Real-time scoring system for GYMRACE fitness competitions

Principal Engineer

Raspberry Pi / Node.js / TypeScript / React +5

BLE and storage redesign

Sparv Embedded

Wearable ECG Monitor Hardware Redesign

System Developer & Hardware Engineer

Hardware Design / PCB Design / Embedded C / BLE +2

1000+ units shipped

Lifee

IoT Health Tracker for Children

Founder & Technical Lead

Hardware Design / Embedded C / FreeRTOS / BLE +4

Next step

Tell me what you're building

Send me a short description of the problem and I'll tell you whether I'm the right fit, what it would cost, and how long it would take. No pitch deck.

Email me Call +46 70 753 73 78

Email: elinor@wigertztech.se
Phone: +46 70 753 73 78
LinkedIn: elinorwigertz