Nexisense MP905 Multi-Gas Detection Sensor | MOS Thick-Film Multi-Pollutant Sensing Module, Empowering Smart Home Air Quality System Integration

In the context of rapid iteration of smart home ecosystems, indoor volatile organic compounds (VOC), formaldehyde (HCHO), benzene series (BTEX), alcohol vapor, and smoke have become core pain points affecting residential health and user experience. Traditional single-gas sensors struggle to cover multi-pollutant scenarios, while multi-sensor array solutions bring increased system complexity, higher power consumption, and cost pressure. The Nexisense MP905 air quality multi-gas detection sensor adopts metal oxide semiconductor (MOS) thick-film process, integrating heater and gas-sensitive layer on a micro Al₂O₃ ceramic substrate, achieving wide-spectrum high-sensitivity response to various reducing/oxidizing gases, providing B-end system integrators with an efficient, integrated indoor air perception solution.

MOS Thick-Film Gas-Sensing Principle and Multi-Gas Response Characteristics

MP905 is based on n-type metal oxide (such as SnO₂ doped with noble metal catalysts) undergoing surface redox reaction with target gas at operating temperature (approximately 200–400℃), leading to changes in depletion layer thickness and thus significant change in element conductivity. The heater provides a stable thermal field, and the gas-sensitive layer undergoes multi-layer thick-film printing process with optimized formulation, ensuring balanced cross-sensitivity and selectivity for the following gases:

• Formaldehyde (HCHO) and aldehydes: typical detection limit<0.05ppm, high response

• Benzene, toluene, xylene (BTEX): strong reducing gases, significant response

• Alcohol, isopropanol and other alcohol vapors

• Smoke, combustion products (CO, unburned hydrocarbons)

• Some ammonia and sulfides

The module has built-in temperature compensation circuit and algorithm correction, controlling zero drift within ±5% during operating temperature fluctuations, response recovery time (T90)<30s, recovery time <60s, suitable for continuous monitoring and intermittent sampling modes.

Key Engineering Performance and System Reliability

• Operating Voltage: DC 5V±0.5V (heater 5V, measurement circuit compatible with 3.3V/5V)

• Power Consumption: Heater preheating phase ≈800mW, steady state<400mW, supports PWM power modulation to reduce average power consumption

• Output Form: Analog voltage (0–5V linear corresponding to conductivity change) or digital UART (TTL level, 9600bps default)

• Sensitivity: Rs/R0 (target gas/clean air resistance ratio) >5 (10ppm formaldehyde), >10 (100ppm alcohol)

• Service Life: >5 years (continuous power-on, normal indoor environment)

• Environmental Adaptation: Operating temperature -10～+50℃, humidity 15～90%RH (non-condensing), anti-interference design reduces background influence from ethanol, CO₂, etc.

These parameters ensure MP905 maintains stability and low false alarm rate in smart home 24h continuous operation scenarios.

Typical Application Scenarios and System Integration Value

Smart Fresh Air and Air Purification System Integration

Embedded inside fresh air hosts or air purifiers as core air quality trigger elements. MP905 monitors VOC/formaldehyde concentration exceeding limits in real time and outputs high level or UART alarm frame, linking to fan speed increase, purification mode activation, or fresh air valve opening, achieving demand-responsive ventilation control, seamless docking with mainstream MCUs (such as ESP32, STM32).

Home/Commercial Gas Alarm and Linkage Control

Integrated into wall-mounted or desktop air quality alarms, supporting docking with smart gateways. Outputs raw Rs value or calibrated concentration estimate via UART protocol, enabling multi-level threshold alarms (e.g., VOC >0.5mg/m³ level 1, >1.0mg/m³ level 2), linking to air conditioners, humidifiers, or exhaust fans, compliant with GB/T 18801 and GB 50346 related standards.

Indoor Environment Monitoring Station and IoT Nodes

Suitable for smart home central control panels, environment monitoring stations, or wireless sensor nodes. Low-power characteristics support battery/solar-powered scenarios, achieving cloud air quality trend analysis, historical data storage, and remote push via UART to LoRa/Zigbee/NB-IoT gateways, contributing to smart community and green building certification.

Selection Guide: Key Parameters for Matching Project Specifications

• Output Type: Analog voltage (simple ADC acquisition)/digital UART (recommended, easy for protocol parsing and remote debugging)

• Heating Voltage: Standard 5V / customizable 3.3V low-power version (preheating time extended but average power consumption reduced by 30%)

• Sensitivity Grading: Standard version (general VOC) / high-formaldehyde version (formaldehyde optimized, response improved by 20%)

• Encapsulation Form: Standard metal shell TO-5 / customizable pin definition, waterproof coating, or dust-proof net

• Preheating Time: Standard 60s / fast preheating version<30s (suitable for intermittent sampling)

Recommended circuit: 5V heating + precision divider resistor to acquire Rs, MCU uses 12-bit ADC to acquire voltage, or directly reads digital value via UART.

System Integration Notes and Best Practices

• Installation Position: Avoid direct blowing from air conditioner outlets and kitchen oil fume direct impact areas, recommend placement at breathing height (1.2–1.5m) or near return air inlets

• Preheating and Aging: After power-on, recommend continuous power-on for 24–48h aging to stabilize zero point and baseline resistance

• Circuit Design: Add current-limiting resistor and filter capacitor to heating circuit to avoid power fluctuation affecting heating temperature; signal lines away from high-frequency interference sources

• Calibration Strategy: Factory calibrated baseline, project-level recommend single-point or two-point field verification in clean air and standard formaldehyde/benzene gas environment

• Long-term Stability: Zero-point re-verification every 6–12 months, consider replacement when Rs/R0 decreases by more than 30%

OEM Customization and Bulk Supply Advantages

Nexisense provides flexible customization services for system integrators and brand owners:

• Sensitivity curve optimization (enhanced for specific gases such as formaldehyde or TVOC)

• Output protocol customization (custom UART frame format, I²C address, analog output range)

• Heating power and preheating time adjustment (low-power version/fast response version)

• Shell encapsulation, silk screen, pin definition, special tray packaging

• Factory grouping calibration report, batch traceability and reliability accelerated life testing

• Long-term supply agreement, inventory buffer and fast sample delivery mechanism

These supports help customers reduce secondary development costs, unify product consistency, and accelerate market response.

Frequently Asked Questions

1. Compared to electrochemical formaldehyde sensors, what are the advantages of MP905 in multi-gas scenarios? MOS wide-spectrum response can simultaneously monitor formaldehyde, benzene series, TVOC, and smoke, while electrochemical sensors are usually for single gas; MP905 requires no electrolyte maintenance, longer lifespan, suitable for long-term continuous operation.

2. How to reduce heating power consumption to adapt to battery-powered devices? Use PWM duty cycle control for heating power (e.g., 50% duty cycle steady-state power consumption reduced to<200mW), combined with intermittent sampling mode (wake up once every 5–10min), average power consumption can be reduced to <50mW.

3. How is cross-influence of humidity and temperature changes controlled? Built-in temperature compensation circuit + algorithm correction, zero drift <±8% in 0–40℃, 30–80%RH; high-humidity environment recommend adding anti-condensation coating or external heating ring.

4. What is the UART digital output protocol format and baud rate? Default 9600bps, 8N1; frame format is start bit + concentration estimate (or Rs value) + status code + checksum, documentation provides complete parsing examples and reference code.

5. How to judge and compensate for sensitivity decline after sensor aging? Monitor baseline resistance R0 change (in clean air); trigger maintenance reminder when decline exceeds 30%, dynamic compensation via software algorithm or module replacement.

6. How to control false alarm rate in complex indoor environments such as cooking fumes and perfume? Optimized gas-sensitive layer formulation reduces response to high-concentration transient interference; system-level recommend multi-sensor fusion (e.g., CO₂ + temperature/humidity) or time filtering algorithm to suppress short-term peak false alarms.

7. What customization options are supported to adapt to different project specifications? Gas priority response adjustment, output interface type (analog/digital), heating voltage, preheating time, shell protection rating, batch calibration threshold grading, etc.

8. How to maintain detection consistency during long-term operation? Zero-point re-verification every 6 months in clean air environment; module design life >5 years, typical continuous operation 3–5 years sensitivity attenuation<20%, supports RESET command to reset baseline.

Conclusion: Partner with Nexisense MP905 to Build a Reliable Indoor Air Quality Perception Foundation

Nexisense MP905 multi-gas detection sensor, with MOS thick-film technology, multi-pollutant wide-spectrum response, low-power design, and high integration, provides efficient air quality perception capability for smart home fresh air, air purification, home alarms, and environmental monitoring projects. It helps system integrators simplify BOM, reduce development barriers, and significantly enhance terminal product air health management performance and user experience.

Welcome smart home solution providers, air purification equipment manufacturers, home appliance integrators, and project engineering teams to contact the Nexisense team for detailed technical specifications, sample testing support, or custom development schemes. We are committed to becoming your reliable partner in the field of indoor air quality perception, jointly promoting upgrades to healthier and smarter living environments.