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thermostat
Medical Instruments
Blood Slide Heater
Precision thermal profiling for medical labs
A precision blood-slide preparation instrument delivered in three months — hand-tuned PID thermal control with programmable multi-step temperature profiles — now in production use at labs.
3 months
Concept to delivery
Two-way
Heater and fan authority
Per-run
Compliance trace logged
- Client
- A medical-equipment client (name withheld — NDA)
- Delivery
- Delivered by our founder at Lattice Innovations
- Role
- Firmware developer — control algorithm, electronics, GUI, logging
- Timeline
- 2019 · delivered in 3 months
Stack
ATmega2560 Embedded C PID control Custom power electronics HMI GUI USB data logging
help The problem
Preparing blood slides for testing is not "heat to X degrees and hold". Samples must follow a thermal profile — a sequence of set temperatures, each held for a set duration — and precision matters: overshoot can damage a sample, and drift ruins repeatability between tests.
build What we built
- Custom electronics for high-frequency switching of the 12 V heat bead, paired with a fan for active cool-down — giving the control loop authority in both directions instead of waiting on passive cooling.
- A PID loop driving heater and fan together, with coefficients tuned empirically against the real thermal mass: collect response data, adjust, re-run, until overshoot, undershoot and steady-state error were minimised.
- A thermal profiling engine — the operator defines an array of (temperature, duration) steps and the instrument executes the full preparation sequence unattended.
- A state machine managing profiles, safety and user interaction, fronted by an HMI-based GUI.
- Compliance logging: every run's temperature trace written to a file on USB as a per-run record for the lab.
check_circle The result
- done Delivered within the three-month target and in production use at labs for blood-sample testing.
- done Control-systems engineering on real hardware, medical-instrument delivery discipline, and full-stack instrument development from power electronics to GUI.