MP135 Air Pollution Gas Sensor DIP-4

Description

The MP135 Air Pollution Gas Sensor is a compact, DIP-4 packaged semiconductor gas sensor designed for general air-quality trend monitoring and the detection of reducing gases such as hydrogen (H₂), carbon monoxide (CO), and alcohol vapors . It is a practical, low-cost choice for applications like automatic exhaust fans, air cleaners, and indoor air quality indicators where a simple, indicative response to air pollution is sufficient.

At the heart of the sensor is a metal oxide semiconductor (MOS) sensing element (typically SnO₂-based) deposited on a miniature Al₂O₃ ceramic substrate. The integrated heater maintains the sensor at its optimal operating temperature. When reducing gases are present, the sensor‘s conductivity increases proportionally with gas concentration. Users can convert this conductivity change into a usable voltage signal using a simple external circuit with a load resistor .

The DIP-4 package features four pins: two for the heater circuit and two for the sensing electrode. The heater requires 5.0V ± 0.1V (AC or DC) and consumes ≤300mW, making it suitable for continuous operation in low-power monitoring devices . The sensor exhibits high sensitivity and quick response/recovery characteristics, with a sensitivity ratio (Rs in air / Rs in 50ppm H₂) of at least 3 .

Important Note: The MP135 is a non-selective MOS sensor. It cannot distinguish between specific gases and is affected by ambient temperature and humidity variations . It provides relative trend data, not calibrated absolute ppm readings for any specific gas. The sensor requires a warm-up time of more than 48 hours before stable operation . It is not waterproof and must be protected from water condensation, high humidity, and corrosive gases. Exposure to organic silicon vapors can permanently destroy sensitivity . For precise, gas-specific measurements, a different sensor type (such as electrochemical or NDIR) is recommended.

Whether you are building a simple air quality alarm, an automatic ventilation controller, or an educational gas-sensing project, the MP135 provides a reliable, cost-effective entry point for detecting common reducing gases in the air.

Features

• MOS semiconductor sensing element — Detects H₂, CO, and alcohol vapors (VOC-like reducing gases)

• DIP-4 package — Standard through-hole format for easy PCB and breadboard integration

• Low power consumption — Heater power ≤300mW at 5.0V

• High sensitivity — Rs(air)/Rs(50ppm H₂) ≥ 3

• Quick response and recovery — Suitable for real-time trend monitoring

• Simple detection circuit — Only requires a load resistor and basic voltage divider

• Good stability and long life — Proven thick-film manufacturing technology

• Wide application range — Air cleaners, automatic exhaust, household/office harmful gas detection

Technical Specifications