apogeeweb title
Home arrow Sensors

arrow left

arrow right

Oct 26 2020

Humidity Sensor: Working, Types, Application and Arduino Guide

Introduction

The humidity sensor is a sensor that measures relative humidity, absolute humidity, or dew point. At present, such sensors are widely used, and are gradually developing in the direction of excellent environmental resistance, long life, and low price.

This article will introduce the working principle, type, classification, application of humidity sensor, and an Arduino tutorial on real-time temperature and humidity monitor. In addition, some basic knowledge like the calculation of relative humidity and absolute humidity is also covered. Let’s waste no more time!

The humidity sensor is a sensor that measures relative humidity, absolute humidity, or dew point. At present, such sensors are widely used, and are gradually developing in the direction of excellent environmental resistance, long life, and low price.

This article will introduce the working principle, type, classification, application of humidity sensor, and an Arduino tutorial on real-time temperature and humidity monitor. In addition, some basic knowledge like the calculation of relative humidity and absolute humidity is also covered.

If you are only interested about the Arduino guide, you can jump to that part from the category, and the video below is about the accuracy test of different temperature and humidity sensor for arduino, which can help you to choose the best one.

Let’s waste no more time!

Check this video to look for the best temperature and humidity sensor for arduino

Catalog

Introduction

Catalog

I How do Humidity Sensors Work?

1.1 Humidity

1.2 Absolute Humidity and Relative Humidity

1.3 How Humidity Sensors Work

II Classification and Common Types of Humidity Sensors

2.1 Classification

2.2 Comparison of Resistive and Capacitive Humidity Sensors

2.3 Four Types of Humidity Sensors with More Applications

2.4 Commonly Used Humidity Sensor Models

III Application of Humidity Sensors

3.1 Typical Uses

3.2 Application Fields

IV Arduino Entry Project: Real-time Temperature and Humidity Detector

4.1 Hardware Preparation

4.2 Software Preparation

4.3 Circuit Connection

4.4 Implementation Code

I How do Humidity Sensors Work?

1.1 Humidity

Before learning the humidity sensor, let's take a look at what humidity is.

Humidity, a physical quantity indicating the degree of air dryness. At a certain temperature, the less water vapor contained in a certain volume of air, the drier the air; the more water vapor, the more humid the air. The degree of air humidity is called "humidity". In this sense, it is often expressed by physical quantities such as absolute humidity, relative humidity, comparative humidity, mixing ratio, saturation difference, and dew point; if it represents the percentage of the weight of water vapor in the wet steam to the total weight (volume) of the steam, it is called the humidity of the steam. The humidity that human body feels comfortable is: the relative humidity is lower than 70%. So the question comes again, what is the relative humidity?

Humidity

Figure1. What is Humidity?

1.2 Absolute Humidity and Relative Humidity

The degree of dryness and humidity of the air, or the physical quantity that indicates how much water vapor it contains, is called humidity. The mass of water vapor contained in a unit volume of air is called absolute humidity. Because it is difficult to directly measure the density of water vapor, it is usually expressed by the pressure of water vapor. The absolute humidity of the air does not determine the speed of water vapor on the ground and the perception of humidity. People call the absolute humidity of air at a certain temperature and the percentage of saturated air pressure at the same temperature as relative humidity.

To be more specific, absolute humidity refers to the mass of water vapor contained in a certain volume of air, and its unit is generally g/m3. The maximum absolute humidity is the highest humidity under saturation. Absolute humidity is only meaningful together with temperature, because the amount of humidity that can be contained in the air varies with temperature, and the absolute humidity is also different at different temperatures, because the volume of air also changes with temperature. But the closer the absolute humidity is to the highest humidity, the smaller its change with temperature.

The following is the formula for calculating absolute humidity:

The formula for calculating absolute humidity

The symbols are:

e-vapor pressure, the unit is Pascal (Pa)

-The gas constant of water = 461.52J/(kg K) T-Temperature, the unit is Kelvin (K)

m-the mass of water dissolved in the air, in kilograms (kg)

V-The volume of air, in cubic meters (m).

Relative humidity (RH)

A hygrometer is recording relative humidity. Relative humidity is the ratio between absolute humidity and maximum humidity. Its value shows how high the saturation of water vapor is. Air with a relative humidity of 100% is saturated air. Air with a relative humidity of 50% contains water vapor that reaches half the saturation point of air at the same temperature. Water vapor in the air with a relative humidity of more than 100% generally condenses. As the temperature increases, the air can contain more water, that is to say, the relative humidity will decrease when the temperature increases with the same amount of water vapor. Therefore, while providing relative humidity, temperature data must also be provided. The dew point can also be calculated from the relative humidity and temperature.

The following is the formula for calculating relative humidity:

The formula for calculating relative humidity

The symbols are:

ρw-absolute humidity, in grams/cubic meter

ρw,max-the highest humidity, the unit is g/m3

e-water vapor pressure, the unit is Pascal

E-saturated vapor pressure, the unit is Pascal

s-specific humidity, the unit is g/kg

S-the highest specific humidity, the unit is g/kg

1.3 How Humidity Sensors Work

Generally, humidity sensors use the following four methods to detect humidity or condensation:

(1) Measure the change in electrical impedance or capacitance caused by moisture absorption, separation, or condensation of moisture-sensitive materials.

(2) Measure the difference in gas thermal conductivity due to changes in humidity.

(3) Measure the change in the resonance frequency of the crystal vibrator due to changes in humidity or condensation.

(4) Measure the attenuation and light absorption and reflection caused by alpha rays passing through water droplets due to changes in humidity.

For example, the characteristic of a humidity sensitive resistor is to cover a film made of moisture-sensitive material on the substrate. When water vapor in the air is adsorbed on the moisture-sensitive film, the resistivity and resistance value of the element will change. One characteristic can measure humidity.

Humidity sensor

Figure2. How a polymeric membrane humidity sensor works

II Classification and Common Types of Humidity Sensors

2.1 Classification

At present, there are many types of humidity sensors on the market, and their application ranges are also different. They are roughly divided into the temperature and humidity ranges used, which can be listed in the following table.

Industry

Scope of application

Operating temperature and humidity range

Uses

Temperature(℃)

Humidity(%PH)

Home appliances

Air conditioning machine

5~40

 

40~70

 

Air conditioning equipment

Dryer

80

0~40

Clothes drying

Electronic range

5~100

2~100

Food heating and conditioning control

VTR

-5~60

60~100

Prevent condensation

Car

Automatic anti-fog

-20~80

50~100

Prevent condensation

Medical treatment

Treatment device

10~30

80~100

Respirator system

Incubator

10~30

50~80

Air conditioning equipment

Industry

Fiber

10~30

50~100

Silk

Dryer

50~100

0~50

Kiln industry, wood drying

Powder moisture

5~100

0~50

Ceramic raw materials

Dry food

50~100

0~50

Food preservation

Electronic Components Manufacturing

5~40

0~50

Magnetic head, LSI IC

Agriculture, Forestry and Livestock

House air conditioning

5~40

0~100

Air conditioning equipment

Tea smoke anti-frost

-10~60

50~100

Prevent condensation

Reptile feeding

5~40

0~50

Increase humidity, health management

Test

Constant temperature and humidity tank

-5~100

0~100

Precision measurement

RF detector

-50~40

0~100

High-precision meteorological measurement

Hygrometer

5~100

0~100

Control recording device

Other

Soil moisture

-20~50

0~100

Plant cultivation, soil and sand collapse

In the above, we have introduced four methods for detecting humidity or condensation. These measurement methods must be selected according to the different test environment. The most commonly used measurement method on the market is the first one because its measurement and signal selection methods are quite simple and cheap. It can be divided into the following six categories if it is distinguished by the difference of its manufacturing materials:

(1) Electrolytes such as LiCl.

(2) Semiconductor materials such as Se and Ge.

(3) MgCr2O4, ZnCr2O4, TiO2, SnO2 and other metal oxide fusion products.

(4) Porous metal oxide film such as Al2O3.

(5) A material made by dispersing conductive powder in a polymer material such as nylon.

(6) Organic or inorganic polymer electrolyte membrane.

Sensors made of moisture-sensitive materials can be roughly divided into 7 categories:

(1) Electrolyte humidity sensor

(2) Polymer humidity sensor

(3) Ceramic humidity sensor

(4) Crystal oscillator humidity sensor

(5) Semiconductor humidity sensor

(6) Thick film humidity sensor

(7) Condensation humidity sensor

Classification

Moisture Sensitive Material

Detection method

Electrolyte

LiCl+Polyviny1 Alcho1 Polystyrene

Resistor

Sulfated film

Resistor

Potassium sulfate membrane

Resistor

LiC1 saturated solution

Resistor

Semiconductor

Se (Ge or Si) vapor deposition film

Resistor

Si+SiO2+PAPA (Polyamino Phenylacetylene)

Resistor

Metal oxides (ceramics)

Fe3O4 Colloid coating film

Resistor

Cr2O3 Ni2O3 Fe2O3

Resistor

Glass ceramic film

Capacitor

Fe2O3-K2O ceramic

Resistor

ZnO-Li2O-V2O5 ceramic

Resistor

Mg Cr2O4 type ceramic

Capacitor

Polymers

Al2O3+ epoxy resin

Resistor or Capacitor

Multi-emulsion resin film

Capacitor

 

Organic material

Celluloid+Carbon

Resistor

Butyr Cellalose

Capacitor

Resin carbon

Resistor

Polyamid+ crystal oscillator

Resonance frequency

2.2 Comparison of Resistive and Capacitive Humidity Sensors

(1) Resistive humidity sensor

The resistive humidity sensor is a sensor that uses the electrical characteristics of the humidity sensor (such as resistance value) to change with humidity to measure humidity. The humidity sensor is generally immersed in an insulating material with a hygroscopic substance, or through evaporation, It is made by coating and other processes to prepare a layer of metal, semiconductor, polymer film and powdered particles. During the moisture absorption and dehumidification process of the moisture-sensitive element, the conduction state of the ion H+ decomposed by water molecules changes, so that the resistance value of the element changes with humidity.

Resistive humidity sensor

Figure3. Resistive humidity sensor

Advantage

1) Compared with the capacitive type, the structure is simpler, and it is easier to achieve mass production and low price.

2) There is no need to consider the capacity between the leads like capacitive sensors, so the sensor can be stretched at will, with greater design freedom.

3) Since the characteristic is a logarithmic change (the degree of change is large), the humidity change is small for the resistance change. (According to this point, for example, the degree of influence of the deviation of the electrode on the characteristics is small, and the instability is also small. Even if there is a slight change, it is difficult to show when converted to humidity.)

Disadvantages

1) The temperature characteristic is larger than that of the capacitive type (0.5%rh/℃), and temperature compensation is usually required.

2) Since the characteristic is a logarithmic change, if the logarithmic conversion is not processed, the linear characteristic will not be obtained.

3) The low humidity range is difficult to detect due to high resistance. (About 20% rh is the limit) In addition, it is easily affected by interference.

(2) Capacitive humidity sensor

Capacitive humidity sensor is a commonly used instrument in humidity sensors. It uses polymer humidity and humidity-sensitive capacitors as the basic humidity-sensing component, and uses a single-chip microcomputer to analyze, process, display and remotely transmit the measurement results. The measurement accuracy is ±2.5 %.

The capacitive humidity sensor is mainly composed of a glass substrate, a lower electrode, a humidity sensitive material, and an upper electrode. The two lower electrodes are connected in series with the humidity sensitive material and the two capacitors formed by the upper electrode. Humidity-sensitive material is a high molecular polymer whose dielectric constant changes with the relative humidity of the environment. When the environmental humidity changes, the capacitance of the humidity sensor changes accordingly, that is, when the relative humidity increases, the humidity sensitive capacitance increases, and vice versa (the capacitance is usually between 48 and 56 pf). The sensor's conversion circuit converts the humidity-sensitive capacitance change into a voltage change, which corresponds to a change in relative humidity from 0 to 100% RH, and the output of the sensor changes linearly from 0 to 1v.

Capacitive soil moisture sensor

Figure4. Capacitive soil moisture sensor

Advantage

1) Generally speaking, low humidity starting from 0% rh can be detected.

2) The capacitance value is relatively close to linear, and no logarithmic change is required.

3) The temperature characteristic is smaller than that of the resistance type (about 0.05~0.1%rh/℃), and temperature compensation is not required for general use.

4) In order to increase the capacitance value, the structure is made into a thin film, and there are more products with a faster response speed than the resistance type.

Disadvantage

1) If the sensor is extended with a lead wire, the capacitance value will change, so it is not suitable to extend the sensor alone. Also, if it is assembled into the device, it is difficult to change the position by the lead wire, so the design freedom is small.

2) The amount of change is relatively small, but a small change in capacitance will cause a large error. Therefore, inexpensive sensors have a large deviation. (The sensors used for measurement also have very high accuracy, but these estimation formulas have been processed.)

3) The fact that the amount of change is small can be said in terms of dependence. But a small change in capacitance will produce a large error. Therefore, a sensor with poor reliability will have a large humidity change.

4) Although the amount of change is small, the deviation and temperature characteristics of other circuit parts will have a greater influence, so be careful when selecting circuit parts.

2.3 Four Types of Humidity Sensors with More Applications

(1) Lithium chloride humidity sensor

● Resistive lithium chloride hygrometer

Certain metal salts (such as lithium chloride LiCI) have strong moisture absorption properties in the air, and their moisture absorption is a certain function of the relative humidity of the air, that is, the greater the relative humidity in the air, the more the moisture absorbed by the lithium chloride. At the same time, the electrical conductivity of lithium chloride, that is, the size of the resistivity changes with the amount of moisture absorption, the more water absorbed, the smaller the resistivity, and vice versa. Therefore, the relative humidity of the air can be determined according to the change in resistivity of lithium chloride. Lithium chloride resistance hygrometer is a meter made of the characteristics of resistivity change after lithium chloride absorbs moisture.

The first lithium chloride electric humidity sensor based on the principle of resistance-humidity characteristics was developed by F.W.Dunmore of the American Bureau of Standards. This kind of element has high precision, simple structure, low price, suitable for a series of advantages such as measurement and control of normal temperature and humidity.

● Dew point lithium chloride hygrometer

The dew-point lithium chloride hygrometer was first developed by Forboro Company in the United States. This type of hygrometer is similar to the above-mentioned resistive lithium chloride hygrometer, but its working principle is completely different. In short, it uses the saturated vapor pressure of a saturated aqueous solution of lithium chloride to work with temperature.

(2) Carbon humidity sensor

The carbon humidity sensor was first proposed by EKCarver and CWBreasefield in the United States in 1942. Compared with commonly used sounding elements such as hair, casing and lithium chloride, the carbon humidity sensor has a fast response speed, good repeatability, The advantages such as no erosion effect and narrow hysteresis ring are eye-catching. The uncertainty of measurement using carbon humidity sensor does not exceed ±5%RH, the time constant is 2~3s at positive temperature, the hysteresis is generally about 7%, and the specific resistance stability is also better.

(3) Alumina hygrometer

The outstanding advantage of alumina sensor is that the volume can be very small (for example, the humidity sensor used in the radiosonde is only 90μm thick and 12mg weight), high sensitivity (the lower limit of measurement reaches -110℃ dew point), and the response speed is fast (generally 0.3 s to 3s), the measurement signal is directly output in the form of electrical parameters, which greatly simplifies the data processing program, and so on. In addition, it is also suitable for measuring moisture in liquids.

(4) Ceramic humidity sensor

Ceramic humidity sensor is also called metal oxide humidity sensor, because its humidity sensing material is made of metal oxide powder through pressure molding and sintering into ceramics. Due to the degree of sintering, many porous objects can be obtained, and water vapor will be adsorbed on the porous surface to form an adsorption layer, and the H+ ions in the adsorption layer will form current carriers due to the adhesion of water vapor. When the humidity is high, the current attached to the layer of water vapor in the adsorption easily flows. The ceramic humidity sensor utilizes this property to convert the humidity change into the output of the impedance value change.

Heating purification type ceramic humidity sensor

Figure5. Heating purification type ceramic humidity sensor

2.4 Commonly Used Humidity Sensor Models

At present, the main manufacturers and typical products producing integrated humidity sensors are Honeywell (HIH-3602, HIH-3605, HIH-3610), Humirel (HM1500, HM1520, HF3223, HTF3223), Sensiron (SHT11, SHT15) type). These products can be divided into the following four types:

Linear voltage output integrated humidity sensor

Typical products are HIH3605/3610, HM1500/1520. Its main feature is the use of constant voltage power supply, built-in amplifier circuit, can output a volt-level voltage signal proportional to the relative humidity, fast response, good repeatability, and strong anti-pollution ability.

Linear frequency output integrated humidity sensor

The typical product is HF3223 type. It adopts a modular structure and is a frequency output integrated humidity sensor. The output frequency is 8750Hz (type value) at 55%RH. When the relative humidity changes from 10% to 95%, the output frequency is reduced from 9560Hz to 8030Hz . This kind of sensor has the advantages of good linearity, strong anti-interference ability, easy to be equipped with digital circuits or single-chip computers, and low price.

Frequency/temperature output integrated humidity sensor

The typical product is HTF3223. In addition to the functions of HF3223, it also adds a temperature signal output terminal and uses a negative temperature coefficient (NTC) thermistor as a temperature sensor. When the ambient temperature changes, the resistance value changes accordingly and is drawn from the NTC terminal, and the temperature value can be measured with a secondary meter.

Single chip intelligent humidity/temperature sensor

In 2002, Sensiron took the lead in the world to successfully develop the SHT11 and SHT15 intelligent humidity/temperature sensors. The overall dimensions are only 7.6 (mm) × 5 (mm) × 2.5 (mm), and the size is similar to that of a match head. Before leaving the factory, each sensor has been precision-standardized in the temperature room, and the standard coefficients are compiled into corresponding programs and stored in the calibration memory. The relative humidity can be automatically calibrated during the measurement process. They can not only accurately measure relative temperature, but also temperature and dew point. The measurement range of relative temperature is 0-100%, the resolution is up to 0.03%RH, and the highest accuracy is ±2%RH. The measuring temperature range is -40℃~+123.8℃, and the resolution is 0.01℃. The accuracy of measuring dew point is <±1℃. When measuring humidity and temperature, the digits of the A/D converter can reach 12 and 14 bits respectively. Using the method of reducing the resolution can increase the measurement rate and reduce the power consumption of the chip. The products of SHT11/15 have good interchangeability, fast response speed, strong anti-interference ability, do not need external components, adapt to various single-chip microcomputers, and can be widely used in medical equipment and temperature/humidity adjustment systems.

HTS221 Capacitive Digital Humidity Sensor

Figure6. HTS221 Capacitive Digital Humidity Sensor

III Application of Humidity Sensors

3.1 Typical Uses

Work in any industry is inseparable from air, and the humidity of the air is directly related to work, life, and production, making the monitoring and control of humidity more and more important. The main applications of humidity sensors are as follows:

(1) Climate monitoring

Weather measurement and forecasting are of great significance to industrial and agricultural production, military and people’s lives, and scientific experiments. Therefore, humidity sensors are essential humidity measuring equipment. For example, resin swelling humidity sensors have been used in meteorological balloon humidity measuring instruments. on.

(2) Greenhouse breeding

Modern agriculture, forestry, and animal husbandry industries have a considerable number of greenhouses. The humidity control of the greenhouse is as important as temperature control. Controlling the humidity in a suitable range for the growth of crops, trees, livestock and poultry is one of the conditions for reducing pests and diseases and increasing yield.

(3) Industrial production

In the textile, electronics, precision machinery, ceramic industry and other sectors, air humidity directly affects the quality and output of products, and must be effectively monitored and regulated.

(4) Storage of goods

Various items have certain adaptability to the environment. If the humidity is too high or too low, the product will lose its original performance. For example, in high-humidity areas, electronic products are seriously damaged in the warehouse, non-metal parts will become moldy, and metal parts will corrode and rust.

(5) Use protection of precision instruments

Many precision instruments and equipment have higher requirements for the working environment. The environmental humidity must be controlled within a certain range to ensure their normal operation and improve work efficiency and reliability. For example, the working humidity of the telephone program-controlled switchboard is better at 55% ±10%. Too high temperature will affect insulation performance, and too low temperature will easily generate static electricity and affect normal operation.

3.2 Application Fields

(1) Humidity measurement system

● When the temperature is below 70°C (usually above -40°C), if the environment is clean, use a polymer sensor, and use a ceramic sensor (heating cleaning regeneration type) for serious pollution. Because of its heating and cleaning process, it cannot be measured continuously and consumes a lot of energy (1-10W). However, it has a long life and can choose a sensor with a longer heating and cleaning cycle during use, such as a chloroapatite ceramic sensor, which is washed once every 2 to 3 months. In addition, the internal heating type consumes less energy than the external heating type.

● Measure the humidity in the range of 70~100℃, use ceramic sensors with heating and cleaning, and perform linearity and temperature compensation to improve accuracy. In order to achieve higher accuracy, a microcomputer is required. Frequent heating and cleaning are required at high temperature and humidity. For example, when the RH is above 80%, it needs 30S cleaning once. It is best equipped with an automatic heating cleaning device.

● Measure the humidity in the range of 100~150℃. In the world, ceramic humidity sensors are mostly used to make high temperature humidity meters.

(2)Automatic control of industrial processes

In order to improve product quality and energy saving, ceramic humidity sensors are usually used for control in product drying systems, reactor humidity control, boiler water vapor leakage detection, integrated circuits or air conditioning in magnetic head processing plants; the humidity control of various air conditioning systems, medical systems can be carried out with polymer or ceramic humidity sensors.

(3) Steam leak detection system

In thermal power stations, nuclear power plants, steam locomotives, boilers and other high-temperature and high-pressure equipment, in order to prevent gas leakage and prevent personal accidents, humidity sensors can be used for leak detection.

(4) Other systems

In home appliances, the humidity sensor can be used for humidity measurement of humidifiers, dehumidifiers, air conditioners, wine cabinets, clothes dryers, etc.

IV Arduino Entry Project: Real-time Temperature and Humidity Detector

4.1 Hardware Preparation

Arduino UNO one

A temperature and humidity sensor

One PCF8574T adapter board

1602LCD one

A piece of breadboard

Several connecting lines

4.2 Software Preparation

Arduino IDE

4.3 Circuit Connection

This project directly uses the PCF8574T adapter board to drive the 1602 LCD display, which will save a lot of Arduino IO ports and save a lot of wiring troubles. PCF8574T adapter board contains four interfaces: VCC, GND, SDA and SCL. Make these connections respectively: VCC - 5V, GND - GND, SDA - A4, SCL - A5.

The temperature and humidity sensor contains 3 pins, viewed from the side with the mesh, from left to right are DATA, VCC, and GND. Make connections like this: DATA - A0, VCC - 3.3V, GND - GND.

Circuit Connection

Figure7. Circuit Connection

4.4 Implementation Code

Experiment Result

Figure8. Experiment Result

/*

* Use temperature and humidity sensor to detect information and display it on the LCD

*/

#include "Wire.h" // Import libraries needed to drive LCD

#include "LiquidCrystal_I2C.h"

#include "dht.h" // Import dht library for temperature and humidity sensor

#define dht_pin A0 // Connect the data port of the temperature and humidity sensor to A0

dht DHT;

// Set up LCD

LiquidCrystal_I2C lcd(0x27,16,2); // 0x27 is the address of the I2C bus

void setup() {

// Delay waiting for system initialization

delay(1000);

// Initialize LCD

lcd.init();

// Turn on the screen backlight

lcd.backlight();

// LCD screen displays Humidity(%):

lcd.print("Humi(%): ");

// LCD screen displays Temp(C):

lcd.setCursor(0, 1);

lcd.print("Temp(C): ");

}

void loop() {

// Read the data of the temperature and humidity sensor

DHT.read11(dht_pin);

// LCD displays the collected temperature and humidity data

lcd.setCursor(8,0);

lcd.print(DHT.humidity,1);

lcd.setCursor(8,1);

lcd.print(DHT.temperature,1);

delay(1000);

}

After the code is compiled without any problem, click the button to upload it to the Arduino UNO board. After the programming is no problem, you can observe the result on the LCD. If there is no change in the humidity, you can try to breathe a sigh of relief at the sensor and you can observe the change in value.

 

Related Articles

  • What is A Knock Sensor&Troubleshooting Guide What is A Knock Sensor&Troubleshooting Guide
    I IntroductionThe knock sensor is an indispensable important component in the electronic control system of the engine. Its function is to detect whether the engine has knocking phenomenon and send the...
  • What is Laser Sensor: Working, Function and Application What is Laser Sensor: Working, Function and Application
    I IntroductionLaser sensor is a kind of sensor which uses laser technology to measure. It is generally composed of laser, optical parts and photoelectric devices. It can convert the measured physical ...
  • Sensor Basics: Types of Sensors & Classification Sensor Basics: Types of Sensors & Classification
    I IntroductionThe types of sensors are very wide, and we can use different criteria to classify them, such as their conversion principles (basic physical or chemical effects of sensor work), their use...
  • Analysis of Eight Anti-jamming Technologies in Sensor Detection Analysis of Eight Anti-jamming Technologies in Sensor Detection
    Summary         This paper summarizes the eight anti-jamming technologies in sensor detection, and analyzes the details of various anti-jamming technologies, s...
  • Capacitive Touch Sensing of Sensors Capacitive Touch Sensing of Sensors
    Do you know what is electrical principles that allow us to detect the presence of a human finger using little more that a capacitor? Let’s learn something of them?Capacitors Can Be SensitiveWithin the...
  • What is a Light Sensor? What is a Light Sensor?
    I IntroductionThe light sensor is developed based on the photoelectric effect principle of semiconductors. It can be used to detect the intensity of ambient light, and it can also be used to detect th...

pinglun 2 comments

    • pingluntus
    • Aldon on 2020/10/30 16:31:02

    This article's so detailed that I do not finish reading(LOL), but I just bookmark this page for future reading. I have a question sir. I want to know what is the typical accuracy of an absolute humidity sensor? It is a bit hard to find the answer in the post. Thank u so much for ur reply!

      • pingluntu
      • author on 2020/10/30 17:01:54
        author

      Re:

      The typical accuracy of an absolute humidity sensor is +3 g/m3; this converts to about ±5% RH at 40°C and ±0.5% RH at 100°C. So glad you like our content.


    • pingluntus
    • Blaze on 2020/10/30 17:39:23

    I would like to know what material is most frequently used for a humidity detector?

      • pingluntu
      • author on 2020/10/30 17:40:46
        author

      Re:

      Metal oxide, polymers, and carbon-based materials are the most frequently used materials for the fabrication of humidity sensors. These materials have low cost and high sensitivity as well as good compatibility.



Leave a Reply

Your email address will not be published.

 
 
   
 
code image
Rating: poor fair good very good excellent