Environmental context you can trust — temperature, humidity and pressure sensing built for real-world instruments
Temperature, relative humidity, and pressure measurements provide essential context for gas sensing, air-quality monitoring, and environmental instrumentation. Variations in ambient conditions can influence sensor performance, safety thresholds, and regulatory compliance. Alphasense Temperature, Relative Humidity (RH) and Pressure sensors are designed to deliver stable, accurate environmental measurements in compact formats that integrate easily into portable and fixed instruments.
Sensor Product Overview
Portable and Fixed Instruments
Designed for multi-parameter gas detectors, environmental monitors, and air-quality instruments where compact size, low power consumption, and stable calibration are essential.
- RHT-A1 – Temperature and Relative Humidity
The RHT-A1 provides accurate temperature and RH measurements in a compact format suitable for portable instruments and indoor air-quality devices. It is commonly used to correct gas sensor outputs, track ambient conditions, and support compliance reporting. The sensor offers fast response and stable performance across typical operating humidity ranges, making it ideal for handheld and wearable platforms. - PRHT-A1 – Temperature, Relative Humidity and Pressure
The PRHT-A1 extends environmental monitoring by combining temperature, RH, and barometric pressure in a single sensor package. By measuring pressure alongside temperature and humidity, the PRHT-A1 enables altitude compensation, volumetric flow correction, and enhanced environmental context in safety and air-quality instruments. It is particularly valuable in portable and fixed systems operating across changing elevations or weather conditions.
Choosing the Right T/RH/P Sensor by Application
Indoor Air Quality & Environmental Monitoring
- RHT-A1 is well suited for indoor air-quality monitors where temperature and RH trends influence comfort, ventilation control, and sensor correction.
- PRHT-A1 is preferred when pressure data supports airflow calculations or environmental normalization.
Portable Gas Detection & Wearables
- RHT-A1 offers low power consumption and fast response for compact, battery-powered devices.
- PRHT-A1 adds pressure sensing for altitude-aware portable instruments used across variable environments.
Calibration, Compensation & Data Logging
- PRHT-A1 supports advanced correction algorithms where pressure, temperature, and humidity all influence gas concentration calculations.
Key Benefits Across the T/RH/P Sensor Portfolio
- Combined environmental measurements simplify instrument design
- Compact and common A-series size formats optimized for portable and fixed systems
- Stable performance across changing humidity and temperature conditions
- Supports gas-sensor compensation and regulatory reporting
Why OEMs Choose Alphasense?
OEMs rely on Alphasense environmental sensors for their integration simplicity, long-term stability, and compatibility with Alphasense gas-sensor platforms. A common electrical and mechanical approach reduces development time and supports scalable multi-sensor designs.
How Temperature / Relative Humidity / Pressure Sensors Work?
Relative Humidity (RH) Measurement
Alphasense RH sensors use a capacitive polymer element whose dielectric properties shift as moisture content changes. When ambient humidity increases, the polymer absorbs water molecules, altering its capacitance. This tiny capacitance change is digitized by an on-chip ADC and corrected using stored factory calibration, delivering stable, ready-to-use %RH readings.
Temperature Measurement
For RHT-A1 and PRHT-A1 sensors, temperature is measured using an integrated band-gap CMOS temperature sensor. As temperature changes, the band-gap voltage shifts in a predictable way. This voltage is digitized by the same internal ADC and processed alongside calibration data to provide accurate, noise-free °C values.
Together, the capacitive RH element and band-gap temperature sensor offer fully compensated digital outputs, enabling precise environmental monitoring over I²C in HVAC, air-quality, portable safety instruments, and consumer devices.
Pressure Measurement (MEMS Barometric Sensors)
Alphasense pressure sensors use a micro-machined capacitive MEMS diaphragm suspended over a sealed reference cavity. Ambient air pressure deflects the diaphragm, altering the capacitance between diaphragm and electrodes. This capacitance shift is proportional to absolute barometric pressure.
A high-resolution ADC and DSP pipeline converts this raw signal into calibrated pressure, altitude, and temperature outputs. All compensation—temperature, linearity, and altitude calculation—is performed on-sensor, minimizing host processing and ensuring stable barometric measurements across environmental extremes.
Why Measure Temperature, RH and Pressure?
Environmental measurements are critical for:
- Correcting gas sensor outputs
- Ensuring accurate air-quality assessments
- Supporting safety alarms and compliance
- Understanding operating conditions in real-world deployments