Description
Automated gas sampling from multi-sample and multi-animal respirometry.
Running experiments in parallel rather than in series greatly increases throughput and makes better use of time and equipment. The RM-8 respirometer multiplexer allows you to select from any one of seven respirometer sample streams with full baselining available at any time on the eighth channel.
Each stream consists of a pair or precision, fast-operating electrical valves. When activated, these valves connect the selected stream to a pair of common ports. The RM-8 can switch between streams and baselines manually or automatically, between or during recordings with appropriate software, such as ExpeData. Manual channel selection, or user-programmed channel selection (up to 99 steps), or daisy-chainable serial (RS-232) channel selection can also be selected. Multiple instruments can be merged to create almost any number of desired sample streams.
What happens to respirometer chambers that are not selected?
The RM-8 allows respirometer chambers that are not selected to be flushed continuously with a user-provided airstream to prevent hypercapnic or hypoxic conditions from developing between readings. Alternatively, the FlowBar-8 mass flow generator can be used to control air-flow independently through all chambers at once, and the RM-8 can then be used to sub-sample the air emerging from each chamber, allowing very fast switching from chamber to chamber. The RM-8 can deliberately prevent any gas flow while the chamber is not selected, thus transforming itself into a stop-flow multiplexer. The stop-flow configuration prevents cross-contamination between samples.
Optional Configurations
NEW “Small volume” configuration includes 1/16” internal tubing to minimize dead space and maximize response times when low flow rates (<100ml/min) are desired or in some stop-flow configurations.
Optional MuxScan II – Electrical Multiplexer
By using this adapter, you can quickly and easily connect up to 8 activity detectors or other transducers (range: 0 to 5V) to your RM-8, and the adapter will select the appropriate detector automatically when its corresponding solenoid valve is energized. All connections are made via research-grade BNC connectors, except for the connection to the multiplexer itself, which is accomplished via a DB-15 connector with attached cable (supplied). The multi-activity adapter also has provision for biasing resistive detectors such as thermistors, light dependent resistors (handy for activity detection at moderate light levels) and phototransistors using either visible light or invisible infrared illumination.
The RM-8 can be configured for flow-through or stop-flow respirometry as demonstrated in the following graphs.
Example of Flow-through Multiplexing on n=4 laboratory mice (flow rates=2 LPM). Baselines are conducted every 2.5 minutes. Note that a dwell time of only 30 seconds is sufficient to determine metabolic rates.
Example of Stop-flow Multiplexing on n=8 chambers each containing n=10 Drosophila (Flow rates=100ml/min). Baselines are conducted every 10 minutes. Note that the integral of each peak is directly proportional to metabolic rates.
