Liquid Sensors Buying Guide: 2022
Fluids in the form of liquid or gases are widely used in IoT edge applications across various industries, including manufacturing, production, robotics, and healthcare. Monitoring liquid has become a difficult task for enterprises that also pose a danger to other electrical and electronic equipment in edge networks. Real-time detection of liquid leakage and tracking the flow of these liquids is essential to keep the ecosystem safe. For this purpose, liquid sensors are deployed to efficiently detect them.
Liquid sensors are deployed at scale from manufacturing to pharmaceutical plants; every sector uses liquid sensors for monitoring applications. In the agricultural sector, soil moisture sensors are used to determine the amount of moisture present in the soil, which is further used to examine the health of the soil and the amount of irrigation required. In industries, liquids like water and other chemicals flow through pipes and determining the presence, level, and parameters like pressure and flow rate is important for the safety and proper functioning of the processes.
All these are done using different liquid sensors like non-contact liquid detectors, soil moisture sensors, water sensors, and water pressure sensors. Manufacturers like DFRobot, Seeed Studio, and SparkFun have different industrial and non-industrial grade sensors that can be integrated with different commercially available microcontrollers and development kits.
Seeed Studio Grove Water Sensor
Seeed Studio Grove water sensor is a non-industrial hobby-based water sensor used to detect the presence of water. It can be used in non-industrial applications and academic projects. It works on the basic principle that undistilled water conducts electricity. The module consists of interlaced ground and sensor signal traces. These traces, when exposed to water, are shorted and send a high signal through the sensor pin. The grove water sensor signal is pulled up using a 1MΩ resistor. It indicates whether the surface is dry, damped, or completely immersed in water. It can be used in projects depicting rainfall detection, water leakage, and tank overflow.
The sensor provides a Grove-compatible interface that can be used to integrate with development boards like Arduino, Raspberry Pi, and BeagleBone. It can be interfaced with both digital and analog pins to detect the presence as well as the amount of water between the traces.
Specifications of Grove water sensor
- Sensor type: Water detection sensor
- Voltage: 4.75V to 5.25V
- Operating Current: 20mA
- Temperature range: 10°C to 30°C
- Humidity range: 10% to 90%
Recommended reading: Seeed Studio Grove Modules (2022 Buyer's Guide)
SparkFun Soil Moisture Sensor
A soil moisture sensor is used to detect the amount of moisture content in sand or similar materials. It has a wide range of applications in the agricultural sector to find the level of water in the soil to determine the health and amount of irrigation required. The two large exposed pads act as probes for the sensors. Both the pads together act as a variable resistor. The more the moisture content in the soil, the better the conductivity between the probes. This results in a higher SIG output as the resistance is reduced. This version of the SparkFun soil moisture sensor includes a 3-pin screw pin terminal pre-soldered to the board for easy wiring and setup.
It is easily compatible with Arduino and other development boards. The SIG pin is connected to the analog input pin of the Arduino to determine the amount of water in the soil. To extend the life of the probes, they are provided with an Electroless Nickel Immersion Gold(ENIG) finish.
Specification of Sparkfun Moisture Sensor
- Sensor type: Soil moisture sensor
- Operating voltage: 3.3V to 5V
- Operating Current: 20mA
Recommended reading: SparkFun Qwiic Sensors Buying Guide: 2022
DFRobot Gravity Non-Contact Liquid level Sensor
DFRobot’s non-contact liquid level sensor is used to detect the level of liquid that can be acids, toxic substances, strong alkalis, and other corrosive chemicals, damaging modules when in contact with them. The Gravity non-contact liquid level sensor provides a solution for this and easy integration using the Gravity 3-pin interface developed by DFRobot.
The sensor works on the principle of measuring the change in capacitance as the liquid level rises. In the absence of liquid, only stray capacitance would be present at the level at which the sensor is mounted. As the liquid level rises and reaches the vicinity of the sensor, the parasitic capacitance of the liquid adds up with the stray capacitance; this increased capacitance is measured by the sensor to determine the level. It utilises advanced signal processing technology by using a powerful chip (XKC-Y25-T12V) with a high-speed operation capacity.
Specifications of Gravity non-contact liquid level sensor
- Sensor Type: Liquid level sensor
- Operating Voltage: DC 5V to 24V
- Operating Current: 5 mA
- Response time: 500 ms
- Operating Temperature: 0 to 105°C
- Humidity: 5% to 100%
- Range for thickness of induction (sensitivity): 0 to 13 mm
Recommended reading: DFRobot Gravity Sensors Buying Guide: 2022
DFRobot Gravity Analog Water Pressure Sensor
The DFRobot Gravity analog water pressure sensor is used to determine water pressure in a tank or a pipe. The Gravity analog water pressure sensor works on the principle of piezoresistive effect. The monocrystalline silicon material, when subjected to pressure, changes its resistivity, causing a change in the resistance of the circuit. The magnitude of change determines the magnitude of pressure in the pipe.
The sensor can be interfaced easily using the Gravity 3-pin interface developed by DFRobot. It can be combined with other sensors, solenoid valves, and water turbines to build a smart water control system. It can also be used in smart home control systems.
Specifications of Gravity analog water pressure sensor
- Sensor type: Water pressure sensor
- Input Voltage: 5V
- Measurement accuracy: 0.5% to 1% FS
- Operating Temperature: -20 to 85°C
- Response Time: <2.0 ms
- Normal Operating Pressure: ≤2.0 Mpa
Recommended reading: Best Arduino Robot Kit
DFRobot Gravity Analog Steam Sensor
The DFRobot Gravity analog steam sensor detects the amount of steam in an enclosed environment. The module uses a Gravity 3-pin interface by DFRobot; it hence can be used with development boards, like Arduino. It can be connected to a digital or analog pin of Arduino to monitor the presence of steam and its magnitude. The module can also be used to build a touch sensor and a simple rain detector.
Specifications of Gravity analog steam sensor
- Power supply: 3V3 to 5V
- Output voltage signal: 0 ~ 4.5V (at 5V) or 0 ~ 3.0V (at 3V3)
- Pin definition: Analog output (blue wire), GND (black wire), power (red wire)
- Size: 30x20x6 mm
Final thoughts on liquid sensors
With the growing demand for enterprise-scale edge deployment, IoT edge devices, such as sensors, have become widely used in several industries. Liquid sensors in specific, have been adopted for agricultural and manufacturing industrial applications. The SparkFun soil moisture sensor can be used by hobbyists who are looking to integrate the sensor into their outdoor agricultural applications. The non-contact liquid level sensor can be interfaced with your favourite development board for detecting the liquid level, which can be acids and chemicals. We are witnessing the launch of new liquid sensors daily from leading embedded manufacturers to serve the ever-growing demand.
Your turn: Have you got any experience with liquid sensors? Let us know which one is your favourite in the comments section below!
Abhishek Jadhav is an engineering student, freelance tech writer, RISC-V Ambassador, and leader of the Open Hardware Developer Community.
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