# The common sensor families

How common sensors for temperature, motion and sound work, and what limits each one.

Page: https://dharanova.com/learn/sensor-families · Track: Sense · Level: Core · Facts last checked 7 October 2026

Read first: [What a sensor actually is](https://dharanova.com/learn/what-is-a-sensor.md), [Analog-to-digital conversion](https://dharanova.com/learn/adc-basics.md)

Diagram: Temperature: a Pt100 platinum RTD reads 100 Ω at 0 °C and rises almost linearly, standardised in IEC 60751; an NTC thermistor falls steeply and non-linearly, so it is linearised in software; a thermocouple gives a voltage from the temperature difference between its junction and cold junction (Seebeck effect), so needs cold-junction compensation. Motion: accelerometer (linear acceleration, including gravity), gyroscope (angular rate; orientation drifts uncorrected), magnetometer (often added for heading). Sound: a MEMS microphone sends PDM or I²S to a host, which decimates or receives it.

## Key points

1. A Pt100 platinum RTD has a resistance of 100 Ω at 0 °C that rises almost linearly with temperature; its resistance-temperature relationship is standardised in IEC 60751. [1][2]
2. An NTC thermistor's resistance falls as temperature rises, steeply and non-linearly, so readings must be linearised in software, for example with the Steinhart-Hart equation, a polynomial fit or a lookup table. [3]
3. A thermocouple generates a voltage from the temperature difference between its junctions (the Seebeck effect), so it needs cold-junction compensation to report an absolute temperature. [4]
4. MEMS inertial sensors combine an accelerometer (linear acceleration, including gravity) and a gyroscope (angular rate); a magnetometer is often added for heading. Gyroscope readings integrate into orientation that drifts over time without correction. [5]
5. Digital MEMS microphones commonly output PDM (pulse-density modulation) or I²S, so the audio arrives already digitised and the host only decimates or receives it. [6][7]

## Where to go next

- [Taking a load cell apart until it makes sense](https://dharanova.com/inside-a-load-cell.md): an engineering note from our team
- [Environmental sensors for VAHA: wiring, how readings reach the app, and two TVOC data-integrity gaps](https://dharanova.com/whitepapers/vaha-environmental-sensors-tvoc-data-integrity.md): a whitepaper from our lab

## Sources

1. [IEC 60751:2022 Industrial platinum resistance thermometers and platinum temperature sensors](https://webstore.iec.ch/en/publication/63753), IEC
2. [A Basic Guide to RTD Measurements (SBAA275A)](https://www.ti.com/lit/an/sbaa275a/sbaa275a.pdf), Texas Instruments
3. [Methods to Reduce Thermistor Linearization Error, Memory, and Power Requirements Over Wide Operating Temperature Ranges (SNOAA12)](https://www.ti.com/lit/an/snoaa12/snoaa12.pdf), Texas Instruments
4. [A Basic Guide to Thermocouple Measurements (SBAA274A)](https://www.ti.com/lit/an/sbaa274a/sbaa274a.pdf), Texas Instruments
5. [BNO055 Intelligent 9-axis absolute orientation sensor datasheet (BST-BNO055-DS000)](https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bno055-ds000.pdf), Bosch Sensortec
6. [MEMS Microphone Direct PDM Input via I2S to a C5515 EVM With Software Decimation (SPRAC51)](https://www.ti.com/lit/an/sprac51/sprac51.pdf), Texas Instruments
7. [ICS-43434 Multi-Mode Microphone with I2S Digital Output datasheet (DS-000069)](https://www.cdiweb.com/datasheets/invensense/emmic-ics43434-ds.pdf), TDK InvenSense (copy hosted by distributor CDI)