Humidity, Moisture Sensors

Part Number	Description / PDF	Quantity
SI7021-A20-GM1R Silicon Labs	SENS HUMID/TEMP 3.6V I2C 2% 6DFN	0
HTU20DF TE Connectivity Measurement Specialties	SENSOR HUMID/TEMP 3V 5% W/FILTER	376
SI7015-A20-GMR Silicon Labs	SENS HUMID/TMP 3.6V I2C 3% 24QFN	0
HIH6130-021-001 Honeywell Sensing and Productivity Solutions	SENSOR HUMID/TEMP 5V I2C 4% SMD	841
HIH6130-000-001 Honeywell Sensing and Productivity Solutions	SENSOR HUMI/TEMP 3.3V SPI 4% SMD	0
T9602-3-A Thermometrics (Amphenol Advanced Sensors)	SENSOR HUMI/TEMP 3.3V PDM 2% MOD	90
CC2A35 Thermometrics (Amphenol Advanced Sensors)	SENSOR HUMID/TEMP 5V PDM 3% SMD	86
SHT21 Sensirion	SENSOR HUMID/TEMP 3V I2C 2% SMD	21281
SC-25 RLE Technologies	SENSOR HUMIDITY 5-95% RH USER	50
IOT-9WD-2 Panduit Corporation	920 MHZ WATER DETECTION SENSOR	4
3721 Adafruit	DIGITAL TEMPERATURE AND HUMIDITY	146
HIH7130-021-001 Honeywell Sensing and Productivity Solutions	SENS HUMID/TMP 3.3V I2C 3% 8SOIC	0
SHT35A-DIS-B2.5KS Sensirion	AUTOMOTIVE SENSOR HUMID/TEMP 1.5	2457
HIH8121-021-001 Honeywell Sensing and Productivity Solutions	SENSR HUMID/TMP 3.3V I2C 2% 4SIP	0
WING-TH RLE Technologies	WIRELESS TEMP HUMIDITY SENSOR	250
SI7022-A20-IM1R Silicon Labs	SENS HUMID/TEMP 3.6V PWM 3% 6DFN	0
SI7015-A20-GM1R Silicon Labs	SENS HUMID/TMP 3.6V I2C 3% 24QFN	0
CC2A33 Thermometrics (Amphenol Advanced Sensors)	SENSOR HUMI/TEMP 3.3V PDM 3% SMD	100
CC2D23 Thermometrics (Amphenol Advanced Sensors)	SENSOR HUMI/TEMP 3.3V I2C 2% SMD	1590
SC-50 RLE Technologies	SENSOR HUMIDITY 5-95% RH USER	50

Humidity, Moisture Sensors

1. Overview

Humidity and moisture sensors are transducer devices that measure and report the water vapor content in air or the water content in materials. Humidity sensors quantify relative humidity (RH) or absolute humidity in g/m , while moisture sensors detect moisture levels in solids/liquids. These sensors play a critical role in industrial process control, environmental monitoring, agriculture, and smart home systems by ensuring product quality, optimizing energy efficiency, and maintaining safety standards.

2. Main Types and Functional Classification

Type	Functional Features	Application Examples
Capacitive Humidity Sensors	Measure dielectric changes in polymer films, high accuracy ( 2% RH), fast response	Industrial HVAC systems
Resistive Humidity Sensors	Use ceramic materials with resistance variation, low cost, moderate accuracy	Consumer electronics
Optical Moisture Sensors	Non-contact measurement via near-infrared absorption, high precision	Food processing quality control
Dielectric Moisture Sensors	Measure permittivity changes in materials, suitable for solids	Agricultural soil monitoring
Thermal Conductivity Sensors	Compare thermal conductivity between dry/wet air, resistant to contaminants	Automotive defrost systems

3. Structure and Components

Typical sensor architecture includes: (1) Sensing element (polymer, ceramic, or optical material), (2) Electrode structure (interdigitated or parallel plates), (3) Signal conditioning circuitry (amplifiers, ADCs), (4) Protective enclosure (IP65-rated housing). Advanced designs integrate MEMS technology for miniaturization and on-chip calibration memory for improved accuracy.

4. Key Technical Specifications

Parameter	Description	Importance
Measurement Range	0-100% RH for humidity, 0-50% moisture content for solids	Determines application suitability
Accuracy	1.5% to 5% depending on type	Quality control in critical processes
Response Time	5-60 seconds for 90% step change	Real-time monitoring capability
Operating Temperature	-40 C to +125 C	Environmental durability
Long-term Stability	Drift <1% RH/year	Reduces calibration frequency

5. Application Areas

Industrial: Semiconductor cleanrooms, paper manufacturing
Agriculture: Smart irrigation systems, grain storage
Medical: Respiratory equipment, pharmaceutical storage
Consumer: Smart thermostats, laundry dryers
Environmental: Weather stations, corrosion prevention

6. Leading Manufacturers and Products

Manufacturer	Product Series	Key Specifications
Honeywell	HIH-5030	0-100% RH, 3.5% accuracy, 15ms response
Sensirion	SHT45	I2C interface, 1.8% RH, -40 C to +125 C
TE Connectivity	HH10K	Low power consumption: 0.5 A standby
Vaisala	HMT333	Industrial temperature range: -40 C to +180 C

7. Selection Guidelines

Key considerations: (1) Environmental conditions (temperature extremes, chemical exposure), (2) Required measurement range and accuracy, (3) Output signal type (analog/digital), (4) Long-term stability vs calibration frequency, (5) Cost constraints. For example, capacitive sensors suit general industrial monitoring, while optical sensors are preferred for food safety applications requiring non-contact measurement.

8. Industry Trends

Emerging trends include: (1) Integration of wireless IoT connectivity (LoRaWAN, BLE), (2) Multi-sensor fusion with temperature/pressure compensation, (3) Development of self-calibrating MEMS-based sensors, (4) Adoption of AI algorithms for predictive maintenance. The market is projected to grow at CAGR of 6.2% through 2030, driven by smart agriculture and healthcare monitoring applications.

9. Application Case

In precision agriculture: Dielectric soil moisture sensors (Decagon Devices EC-5) enable automated irrigation systems with 1% volumetric water content accuracy, reducing water usage by 30% in greenhouse tomato cultivation.