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Ocean Observation: From Microfluidics to Global Scale
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Microfluidic Biogeochemical sensors for global scale observation (Invited)
Tuesday 8th @ 1350-1410, Conference Room 7
Matthew Mowlem* , National Oceanography Centre, European Way, Southampton, UK
Presenter Email: matm@noc.ac.uk |
| Microfluidic sensors (also known as lab on chip) enable adapted traditional reagent based analytical techniques for chemistry and biology to be performed in situ, e.g. submerged in the marine environment. Recently this has included use on landers and moorings, profiling floats (PROVOR, NKE, France), ocean gliders (Seaglider, Kongsberg, Norway) and AUVs (e.g. Autosub Long-Range, NERC, UK). This approach is advantageous as the metrology quality is assured by using high performance assays. In addition, standards and blanks can be carried allowing in situ calibration to improve accuracy and to address drift. Recent deployments (including >1 year in the Arctic) indicate that challenges from biofouling and reliability, particularly of moving components, have been adequately addressed. We present a family of microfluidic sensors that use a common component set with subtle design and more fundamental assay variations to provide high performance operational measurement of a number of parameters including nutrients (e.g. nitrate, nitrite, phosphate, silicate), micronutrients (e.g. Iron), and the ocean carbonate system (pH, TA, DIC). Assays and sensors for further parameters (e.g. RNA and DNA) are in development. The sensors use a network of microchannels formed in a polymer substrate to mix sample (sea) water (or standards or blanks) with reagents to produce a colour or conductivity change in response to changes in the parameter of interest. Physically they consist of a microfluidic manifold (chip) on which is mounted a high performance multi-barrel syringe pump and microvalves to enable fluid manipulation within the manifold and optical, electrical or temperature sensors for analytical determinations. Columns for extraction and concentration of analytes or conversion to reactive forms (e.g. from Nitrate to Nitrite, the latter reacting with the Greiss reagent for determination) can be attached to the manifold. The system is controlled with embedded microelectronics and interfaces with a wide range of communication systems and platforms. The systems are robust over a wide range of temperature (<-10 oC to >30 o C) and pressure (tested to 60 MPa) allowing for a wide range of deployments and applications in a variety of aquatic environments. |
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