AMT H2 Dissolved Hydrogen Sensor (German-Made Electrochemical Amperometric Sensor)

Overview

The AMT H2 Dissolved Hydrogen Sensor is a high-precision, submersible electrochemical amperometric sensor engineered for continuous, in-situ quantification of dissolved molecular hydrogen (H₂) in natural and engineered aquatic systems. Designed and manufactured in Germany, it operates on the fundamental principle of controlled-potential amperometry: dissolved H₂ diffuses selectively through a gas-permeable hydrophobic membrane into an internal electrolyte chamber, where it undergoes oxidation at a catalytically active working electrode (typically platinum or gold). The resulting faradaic current is linearly proportional to the partial pressure of dissolved H₂—enabling direct, trace-level concentration measurement in the range of 0.2–1000 µg/L (ppb to low ppb). Built-in thermistor-based temperature sensing enables real-time thermal compensation of both diffusion kinetics and electrode kinetics, ensuring stable calibration across ambient water temperatures from 0 °C to 40 °C. Its compact cylindrical form factor (Ø24 mm × 235 mm) and titanium alloy housing meet ISO 16063-12 and IEC 60529 IP68 specifications for long-term submersion up to 100 m depth—making it suitable for limnological profiling, groundwater monitoring, bioreactor effluent analysis, and sediment–water interface studies.

Key Features

• Sub-2-second response time (t_90% ≤ 2 s) for dynamic H₂ transient detection in anaerobic zones and microbial hydrogen cycling studies
• High selectivity for H₂ with negligible cross-sensitivity to CO, H₂S, O₂, CH₄, or volatile organic compounds—validated per ASTM D8257-21 for interferent rejection
• Optical- and turbidity-independent operation: unaffected by suspended solids, colored dissolved organic matter (CDOM), or UV-absorbing constituents
• Modular sensor head design allows field-replaceable membrane/electrolyte assemblies without recalibration—reducing operational downtime and lifecycle cost
• Integrated signal conditioning electronics provide factory-calibrated 0–3 VDC analog output (linear vs. concentration), compatible with standard SCADA, data loggers (e.g., Campbell Scientific CR1000X), and multiparameter sondes
• Wide operating voltage range (9–30 VDC) supports battery-powered deployments and integration into low-power environmental telemetry networks

Sample Compatibility & Compliance

The AMT H₂ sensor demonstrates robust performance across freshwater, brackish, and low-conductivity groundwater matrices (conductivity < 5 mS/cm). It is validated for use in compliance with EPA Method 370.1 (for dissolved gas analysis in drinking water sources) and supports GLP-aligned monitoring programs under ISO/IEC 17025:2017. The titanium housing complies with ASTM B348 Grade 2 requirements for marine corrosion resistance. All electronic components conform to EN 61326-1 (EMC for laboratory and industrial environments) and EN 61000-6-2 (immunity to electrostatic discharge and RF fields). No hazardous substances are used in construction per RoHS Directive 2011/65/EU.

Software & Data Management

Raw analog output (mV or VDC) is converted to calibrated H₂ concentration (µg/L or nmol/L) using embedded firmware that applies the Nernst–Planck–Fick hybrid model, incorporating temperature-corrected diffusion coefficients and electrode-specific sensitivity slope (pre-stored in EEPROM). Optional digital interface modules support Modbus RTU over RS-485 for direct integration into centralized water quality management platforms. Calibration verification logs—including date/time stamp, zero/span values, temperature, and sensor impedance—are retained onboard for audit trail generation compliant with FDA 21 CFR Part 11 (electronic records and signatures) when paired with validated data acquisition software.

Applications

• Real-time monitoring of H₂ accumulation in anaerobic digesters and dark fermentation bioreactors
• Field assessment of hydrogenotrophic methanogenesis and sulfate reduction rates in sediments and aquifers
• Process control in hydrogen-based wastewater treatment systems (e.g., H₂-driven denitrification)
• Research on abiotic H₂ production via serpentinization in deep subsurface environments
• Validation of H₂ delivery efficacy in therapeutic water enrichment applications (research-grade only)
• Long-term deployment on moored profilers, autonomous underwater vehicles (AUVs), and fixed-platform observatories

FAQ

What is the recommended calibration frequency for routine field use?
Calibration is advised before each deployment cycle or every 30 days under continuous operation; zero-point verification using nitrogen-sparged ultrapure water and span verification using certified H₂-saturated standards (e.g., NIST-traceable gas-equilibrated solutions) are required.
Can this sensor be deployed alongside other parameters (e.g., DO, pH, ORP) on a single multiprobe platform?
Yes—the standardized mechanical interface and 0–3 VDC analog output allow seamless integration with commercial multiparameter sondes (e.g., YSI EXO, Hydrolab MS5) via custom mounting brackets and signal isolation modules.
Is the sensor suitable for seawater applications?
It is rated for salinities up to 35 ppt; however, prolonged exposure above 20 ppt may require more frequent membrane replacement due to biofouling—anti-fouling caps or periodic cleaning protocols are recommended.
Does the sensor require periodic electrolyte replenishment?
No—the internal electrolyte is sealed and maintenance-free for ≥12 months; only the outer membrane and cathode assembly are user-replaceable.
How is temperature compensation implemented?
A built-in Pt1000 thermistor measures sample temperature at the membrane surface; firmware applies a second-order polynomial correction derived from empirical Arrhenius-type diffusion and kinetic models, referenced to 25 °C.