Inputs are crucial for both monitoring and automation systems. Inputs are commonly thought of as sensors, often measuring environmental conditions, such as temperature and humidity, but inputs can also be devices such as cameras, web queries, or other hardware or software processes. Monitoring provides the ability to record historical measurement data, which can be useful for tracking trends or forecasting future events. Automation uses measurement data to create feedback loops with control devices, allowing regulation of a number of different processes, such as temperature, humidity, air flow, gas concentrations, water level and flow, to name a few. Without measurements, a control system is blind and cannot effectively know to what degree an output device should be modulated.
There are many types of sensors, for nearly every thing that can be measured. Most applications involving automation have revolved around just a few measurement types. With the number of sensors on the market, determining the quality of sensors is important to selecting the right one. Here is a curated list of sensors that have worked well for a number of my applications.
If you want to begin learning about and developing automation systems, I recommend my software, Mycodo, and a single board computer. All the devices listed here are quality products and are supported by Mycodo.
Acceleration
Altitude
Carbon Dioxide, CO2 (Air)
Distance
Dissolved Oxygen (Liquid)
Electrical Conductivity (Liquid)
Electrical Potential, Voltage (Analog-To-Digital Converter)
Flow (liquid)
Humidity
Ion Potential, pH (Liquid)
Light/Color
Magnetic Flux
Oxidation Reduction Potential (Liquid)
Particles (Air)
Pressure (Atmospheric)
Pressure (High Pressure)
Temperature
Temperature (Wide Temperature Range)
Temperature (Non-Contact)
All Sensors
ADS1115
Measures: Electrical Potential (Voltage, analog-to-digital converter)
Channels: 4
Resolution: 16-bit
Links: Manufacturer, Datasheet
Buy: Amazon, DFRobot
A great high-resolution analog-to-digital converter for general voltage-measuring applications, such as with analog sensors and devices.
ADS1256
Measures: Electrical Potential (Voltage, analog-to-digital converter)
Channels: 8
Resolution: 24-bit
Links: Manufacturer, Datasheet
Buy: Amazon
This is a great analog-to-digital converter if you need extremely high resolution measurements, such as when measuring very small voltages or voltage changes.
ADT7410
Measures: Temperature
Resolution: 16-bit
Accuracy: ± 0.5 °C
Links: Manufacturer, Datasheet
Buy: Adafruit
This is a high-accuracy temperature sensor.
ADXL345
Measures: Triple-Axis Acceleration (g-force)
Resolution: 10-bit
Sensitivity: ± 2 g, ± 4 g, ± 8 g or ± 16 g
Links: Manufacturer, Datasheet
Buy: Amazon, DFRobot
AM2315
Measures: Humidity, Temperature
Buy: Adafruit
The AM2315 is a temperature and humidity sensor that stands out because it comes with a housing with a porous filter and mounting hardware. There can be some tweaking of the I2C parameters to get it to work well, but it often produces reliable and accurate results.
AMG8833
Measures: Temperature (Non-contact)
Buy: Amazon
This packs an 8 x 8 grid of thermal IR sensors to provide 64 separate non-contact temperature measurements. This effectively allows you to measure the temperatures across an area from a distance.
Anyleaf EC
Measures: Electrical Conductivity
Buy: Anyleaf
This is an electrical conductivity meter that is an inexpensive alternative to higher cost meters such as Atlas Scientific.
Anyleaf ORP
Measures: Oxidation Reduction Potential
Buy: Anyleaf
This is an oxidation reduction potential meter that is an inexpensive alternative to higher cost meters such as Atlas Scientific.
Anyleaf pH
Measures: Ion Concentration (pH)
Buy: Anyleaf
This is a pH meter that is an inexpensive alternative to higher cost meters such as Atlas Scientific.
AS7262
Measures: Light/Color
Buy: Amazon
BH1750
Measures: Light
Buy: Amazon, DFRobot
BME680
Measures: Altitude, Humidity, Pressure, Temperature
Buy: Amazon, DFRobot 1, DFRobot 2
BMP280
Measures: Altitude, Pressure, Temperature
Buy: Amazon, DFRobot 1, DFRobot 2
CozIR CO2
Measures: Carbon dioxide (CO2)
Range: 0 – 10,000 ppmv
Buy: CO2Meter
There are two types of the CozIR carbon dioxide sensors, with multiple versions. The CO2Meter link will take you to their search results for “CozIR”.
DPS310
Measures: Pressure, Temperature
Buy: Amazon
DS18B20
Measures: Temperature
Accuracy: ± 0.5 °C
Resolution: 12-bit
Interface: 1-Wire
Buy: Amazon, DFRobot 1, DFRobot 2
The DS18B20 1-wire sensor is a very common and reliable temperature sensor that runs on the 1-wire interface, which requires only one data wire. Multiple sensors can be connected to the same data wire and are accessed by a unique 64-bit ID burned in at the factory to differentiate them.
EZO-CO2 (Carbon Dioxide)
Manufacturer: Atlas Scientific
Measures: Carbon dioxide (CO2)
CO2 Range: 0 – 10,000 ppmv
Accuracy: (± 5 %) + (± 50 ppm)
Resolution: 1 ppmv
Humidity Range: 0 – 95 % non-condensing
Life Expectancy: ~5.5 years
Interface: I2C, UART, FTDI
Buy: Amazon
Atlas Scientific’s CO2 sensor has the circuit board potted (sealed in epoxy) and encased in a threaded metal body for easy mounting. It has good accuracy and a long life expectancy.
EZO-DO Dissolved Oxygen Kit
Manufacturer: Atlas Scientific
Measures: Dissolved Oxygen
Range: 0 – 100 mg/l
Accuracy: ± 0.05 mg/l
Life Expectancy: ~4 Years
Interface: I2C, UART, FTDI
Buy: Amazon
Atlas Scientific’s dissolved oxygen kit is everything you need to start measuring dissolved oxygen in your hydroponic system, aquarium, or other liquid. The probe is lab-grade and is designed for continual immersion.
EZO-EC Electrical Conductivity K 1.0 Kit
Manufacturer: Atlas Scientific
Measures: Electrical Conductivity
Range: 5 − 200,000 μS/cm
Accuracy: ± 2 %
Life Expectancy: ~10 years
Interface: I2C, UART, FTDI
Buy: Amazon
Atlas Scientific’s electrical conductivity kit is everything you need to start measuring electrical conductivity in your hydroponic system, aquarium, or other liquid.
EZO-FLOW
Manufacturer: Atlas Scientific
Measures: Flow (fluid), Total Volume
Interface: I2C, UART, FTDI
Buy: Amazon (EZO board), Amazon (3/8″ meter), Amazon (1/4″ meter), Amazon (1/2″ meter), Amazon (3/8″ kit)
EZO-HUM (Humidity)
Manufacturer: Atlas Scientific
Measures: Humidity, Temperature
Range: 0 – 100 %
Accuracy: ± 2 %
Life Expectancy: 10 years
Interface: I2C, UART, FTDI
Buy: Amazon
Atlas Scientific’s humidity sensor has the circuit board potted (sealed in epoxy) and encased in a threaded metal body for easy mounting. It uses the HTU21D-F sensor, but because everything is potted, it can be safely used in high humidity environments without risking damage to the circuit board.
EZO-ORP Oxidation Reduction Potential Kit
Manufacturer: Atlas Scientific
Measures: Oxidation Reduction Potential
Range: ± 2000 mV
Accuracy: ± 1 mv
Life Expectancy: 2+ Years
Interface: I2C, UART, FTDI
Buy: Amazon
Atlas Scientific’s oxidation reduction potential kit is everything you need to start measuring oxidation reduction potential in your hydroponic system, aquarium, or other liquid. The probe is lab-grade and is designed for continual immersion.
EZO-PH pH Kit
Manufacturer: Atlas Scientific
Measures: Ion Concentration (pH)
Range: 0 – 14
Resolution: ± 0.001
Accuracy: ± 0.002
Life Expectancy: ~2.5+ Years
Interface: I2C, UART, FTDI
Buy: Amazon
Atlas Scientific’s pH kit is everything you need to start measuring pH in your hydroponic system, aquarium, or other liquid. The probe is lab-grade and is designed for continual immersion.
Gravity Analog pH Kit
Manufacturer: Atlas Scientific / Gravity
Measures: Ion Concentration (pH)
Range: 2 – 13
Resolution: ± 0.1
Accuracy: ± 0.1
Life Expectancy: ~12 – 18 months
Interface: I2C, UART, FTDI
Buy: Amazon
This is a less expensive alternative to the Atlas Scientific EZO-PH pH Kit, above. It uses the Gravity analog pH sensor board (instead of the EZO-PH board) and consumer grade pH probe (instead of a lab grade probe). This probe is not meant for constant immersion like the lab-grade probe in the EZO-PH kit.
EZO-PRS (Pressure)
Manufacturer: Atlas Scientific
Measures: Pressure
Range: 0 – 50 PSI
Resolution: 0.001
Accuracy: ± 2% (1 PSI)
Interface: I2C, UART, FTDI
Buy: Amazon
Atlas Scientific’s pressure sensor has the circuit board potted (sealed in epoxy) and encased in a threaded metal body for easy mounting. It is designed to measure higher pressures than atmospheric pressure sensors.
EZO-RGB (Color)
Manufacturer: Atlas Scientific
Measures: Light/Color
Reads: RGB (24-bit), CIE (xyY), LUX (0 – 65535)
Sensing Area: 15° half angle
Interface: I2C, UART, FTDI
Buy: Amazon
Atlas Scientific’s color sensor has the circuit board potted (sealed in epoxy) and encased in a threaded metal body for easy mounting. It includes 6 LED lights for illuminating the object being measured.
High Temperature PT-1000 Temperature Kit
Manufacturer: Atlas Scientific
Measures: Temperature
Range: -200°C – 850°C
Accuracy: ± (0.15 + (0.002 * t)) °C
Life Expectancy: 15 years
Interface: I2C, UART, FTDI
Buy: Amazon (30 mm thermowell), Amazon (50 mm thermowell), Amazon (100 mm thermowell)
Atlas Scientific’s temperature sensor kit is a resistance temperature detector (RTD) designed to measure a wide range of temperatures. With the included thermowell, extreme temperatures can be measured, where other sensors would fail. Any other PT-100 or PT-1000 probe can also be used with this sensor board.
High Temperature K-Type Thermocouple Kit
Manufacturer: Gravity
Measures: Temperature
Range: -270°C – 1372°C
Resolution: 14-bit, 0.25 °C
Accuracy: within ≤ ±2°C (-200°C ~ 700°C); ±4°C (700°C ~ 1350°C)
Interface: I2C
Buy: DFRobot
This is similar to the Atlas Scientific sensor kit for measuring a wide range of temperatures, but with a lower accuracy and lower cost, as a result of the use of a thermocouple rather than an RTD. Any other K-Type thermocouple probe can be used with this sensor board.
HTU21D-F
Measures: Humidity, Temperature
Buy: Amazon
This is the same sensor in the Atlas Scientific EZO-HUM, but is on a breakout board that is unprotected from the environment. If you want to use this in very high humidity environments, consider the EZO-HUM that has its circuitry potted (sealed in epoxy).
K-30
Measures: Carbon dioxide (CO2)
Technology: Non-dispersive infrared (NDIR)
Range: 0 – 10,000 ppm
Accuracy: ± 30 ppm ± 3 % of measured value
Life Expectancy: > 15 years
Interface: Serial, Analog
Buy: CO2Meter
This is a fairly reliable carbon dioxide sensor. Automatic Baseline Calibration is enabled by default, so unless you disable this functionality, it should not be used in sealed environments (grow rooms) that do not experience environmental CO2 levels (~400 ppm) periodically. If you are using this for a grow room, ensure you contact the manufacturer to order the version with ABC turned off.
MAX30301
Measures: Particles
Buy: Amazon
MCP9808
Measures: Temperature
Buy: Amazon, DFRobot
MH-Z19B
Measures: Carbon dioxide (CO2)
Buy: Amazon
This is an economical and accurate CO2 sensor. This is the model B version that allows Automatic Baseline Calibration (ABC) to be turned off, which is useful for measuring sealed environments that don’t experience environmental CO2 levels (~400 ppm) periodically. With ABC enabled, the sensor must experience ~400 ppm CO2 periodically in order to self-calibrate; if it doesn’t it will self-calibrate to whatever it measures as the lowest measured CO2 concentration to 400 ppm, and preventing future measurement accuracy.
MLX90393
Measures: Magnetic Flux
Range: ±5 mT up to ±50 mT in all 3 axes
Resolution: 16-bit
Buy: Amazon
This is a non-contact three-dimensional hall sensor for measuring magnetic flux (magnetic fields). When compared to most magnetometers, this provides a huge measurement range, which means it’s great for detecting magnets and magnetic orientation, rather than the magnetic field of the Earth, since magnets often have a much stronger field that overwhelms most magnetometers (which would normally be used for orientation relative to the North Pole).
SCD30
Manufacturer: Sensirion
Measures: Carbon dioxide (CO2), humidity, temperature
CO2 Range: 400 – 10,000 ppmv
Accuracy: ± (30 ppm + 3 %)
Operating Relative Humidity Range: 0 – 95 % non-condensing
Life Expectancy: 15 years
Links: Manufacturer, Datasheet
Buy: Amazon
SHT31
Measures: Humidity, Temperature
Buy: Amazon, DFRobot 1, DFRobot 2
TMP006
Measures: Temperature (Non-contact and die)
Buy: Adafruit
VL53L1X
Measures: Distance
Range: 400 cm
Accuracy 4 mm
Buy: Amazon
ZH03B
Measures: Particles
Buy: AliExpress
