Temperature Sensor Comparison¶
Run the Temperature Sensor Comparison MicroSim Fullscreen
About This MicroSim¶
Chapter 2 introduced measurement range as a specification that rules sensors in or out. This is what that looks like.
Four families on one axis:
| Sensor | Range | Sensitivity | Linearity | Cost |
|---|---|---|---|---|
| Thermocouple (type K) | −200 to 1350 °C | low | fair | low |
| Resistance thermometer (Pt100) | −200 to 850 °C | moderate | excellent | high |
| Thermistor (NTC 10k) | −55 to 150 °C | very high | poor | very low |
| Silicon diode (BME280) | −40 to 85 °C | moderate | good | low |
The temperature axis is deliberately broken: 450 degrees below 200 °C get 70% of the width, and the remaining 1600 degrees share the rest. Without that, the −50 to 150 band where almost every reading in this book lives would be an unreadable sliver. The break is marked on the axis with a red glyph and named in the axis title.
Pick a scenario and watch sensors get ruled out. The Minnesota one is the interesting case: all four are technically in range for −40 to +40, but the BME280's floor is exactly −40, and Minnesota's record low is −51 °C, set at Tower in 1996. On that night your station would not read badly. It would stop reading.
The response curves view answers the obvious follow-up question. Platinum is almost perfectly straight and the thermistor curves hard - and those are the same fact seen twice, because curving hard is what being very sensitive looks like on a graph. High sensitivity and good linearity pull in opposite directions.
How to Use¶
- Hover a bar for its exact range, sensitivity, linearity and cost.
- Click a bar for how that sensor actually works.
- Press a scenario button. Sensors that cannot do the job dim, and the panel says why.
- Switch to Response curves and compare the shapes.
- Note the red break glyph on the temperature axis. The scale changes there.
Iframe Embed Code¶
You can add this MicroSim to any web page by adding this to your HTML:
<iframe src="https://iowerx.github.io/pi-env-monitor/sims/temperature-sensor-comparison/main.html"
height="606px"
width="100%"
scrolling="no"></iframe>
Lesson Plan¶
Grade Level¶
6-12
Duration¶
20-25 minutes
Bloom's Taxonomy Level¶
Evaluate (L5)
Prerequisites¶
- Chapter 2 on measurement range
- Reading a horizontal bar chart
Activities¶
- Read the ranges (5 min): Without pressing any scenario button, write down which sensor you would pick for a freezer monitor, a car engine, and a pizza oven. Then check each one against the bars.
- Rule things out (8 min): Work through all four scenarios. For each, list which sensors were ruled out on range alone and which on some other ground.
- The trade-off (8 min): Switch to Response curves. Explain in two sentences why the thermistor is both the most sensitive and the hardest to use.
Assessment¶
- Recommends a sensor for a stated job and defends it against at least two rejected alternatives.
- Uses range as a disqualifier before considering cost or sensitivity.
- Explains the tension between sensitivity and linearity.
References¶
- NIST: ITS-90, the International Temperature Scale - why platinum defines the scale.
- Wikipedia: Thermocouple - including the type K range used here.
- Wikipedia: Thermistor - the exponential response plotted in the curves view.
- Bosch Sensortec BME280 datasheet - the minus 40 to 85 deg C limits this book lives inside.