Hamilton ARC Dissolved CO₂ Probes (CO₂NTROL)

Hamilton CO₂NTROL is a solid-state, in-line dissolved CO₂ sensor that lets you treat CO₂ like any other live process variable instead of a periodic lab check. It measures dissolved carbon dioxide (DCO₂) directly in the bioreactor, in real time, over a working range designed for bioproduction (5 to 1000 mbar, which corresponds to up to ~1500 mg/L in the liquid phase at standard conditions), so you can actively control sparging, stripping, and feed strategy to protect cell health, stabilize metabolism, and improve titer and batch-to-batch consistency across scale-up.

Traditional Severinghaus-style CO₂ probes infer CO₂ indirectly using an internal pH measurement and an electrolyte reservoir, which means drift, liquid handling, and frequent recalibration. CO₂NTROL instead uses a solid-state mid-IR / NDIR optical measurement: CO₂ crosses a gas-permeable interface and the sensor reads CO₂-selective infrared absorption directly, with built-in temperature compensation. That architecture eliminates refillable electrolyte and consumable internals, so there’s no CO₂ consumption, no ammonia fouling, and effectively no ongoing maintenance beyond simple recertification in air / certified gas. Hamilton emphasizes that calibration is done in air and gas standards instead of elaborate multi-point wet calibration, and that the sensor is intended to run maintenance-free through production cycles.

Because CO₂NTROL is part of Hamilton’s Arc family, the transmitter lives inside the probe. The probe speaks RS-485 Modbus RTU directly and stores its own calibration, health, and diagnostic data in onboard electronics, so Daisy Process can pull live DCO₂ and temperature without an external transmitter.

Mechanically, CO₂NTROL RS485 is built for upstream bioprocess. It’s a hygienic, EHEDG-approved design (EL Class I with Hamilton’s sanitary socket) using 1.4435 stainless steel wetted metal surfaces polished to Ra < 0.4 µm, plus EPDM and FDA-listed silicone elastomers. It mounts like a standard PG13.5 process probe and is offered in common “a-lengths” (insertion depths) such as 120, 160, 225, 325, and 425 mm, so you can drop the same sensor concept into R&D glass reactors, pilot skids, and production stainless. Hamilton specifies autoclave, SIP, and CIP compatibility, steam sterilizability up to about 140 °C, and operating pressures from roughly −1 to 12 bar, which means you can sterilize it like your pH / DO probes and then run it continuously without babysitting. In short: it’s inline DCO₂ as a first-class control parameter, not an offline assay.

Technical specs (typical CO₂NTROL RS485)

• Measurement principle: Solid-state optical / mid-IR (NDIR) absorption of CO₂-selective wavelengths with temperature compensation; no electrolyte required and no CO₂ consumed.
• Process value: Dissolved CO₂ reported directly; configurable readout units include mbar, mmHg, hPa, %vol, %sat, and mg/L / ppm equivalents, plus built-in temperature (NTC 22 kΩ).
• Range / accuracy: ~5–1000 mbar (~0.5–100 %vol or ~7.5–1500 mg/L at 25 °C, 1 atm); accuracy at 25 °C is ±5 mbar from 5–100 mbar and ±5% above 100 mbar.
• Digital interface: RS-485 Modbus RTU (Arc); Daisy Process reads this natively as a digital sensor.
• Form factor: PG13.5 process connection; available a-lengths such as 120 / 160 / 225 / 325 / 425 mm to match typical bioreactor ports from lab to production.
• Hygiene & compliance: EHEDG EL Class I hygienic design, stainless steel 1.4435 with Ra < 0.4 µm, EPDM and silicone meeting FDA 21 CFR 177.2600, ready for GMP documentation.
• Sterilization & conditions: Autoclave / SIP / CIP capable; steam sterilizable to ~140 °C; specified operating temp −10 to 140 °C (CO₂ reading available up to ~60 °C); pressure window roughly −1 to 12 bar.