The Components of the Oxylet 4 1. Air Supply Unit This is a source of atmospheric air that can produce flows of up to 20 l/min. This air is sent to the animal cages controlled individually for each one of them by a flowmeter (0-5 l/min, for rats up to 1kg). This unit contents a switching system as well. The aim of this system is to link the metabolic chambers to the O2/CO2 analyser. It should also permit the entry of reference air into the sensors, allowing the comparison of the levels of O2/CO2 between air coming from the chambers and the atmospheric air. This mechanism works thanks to 5 electrovalves that permit to take an air sample from a different cage every x seconds. Every chamber has assigned 2 channels for recording on line O2 and CO2. The measuring of every chambers air is sequentially performed.
2. Metabolic Chambers These are the cages were the animals stay, they are airtight premises (current transparent) with three access routes: one for air input, another for air output and a third for sampling. A fourth access route may be necessary if temperature measurement inside the chamber is included in the equipment. The chambers are described in terms of volume. 9 L chambers are used for rats, whereas mice use 3 L chambers. They all have removable covers, with side fixing and a draft excluder for sealing. There are two kinds of chamber: for measurements taken at rest or for measurements under controlled exercising conditions.
3. Desiccator Columns The air passes through these columns after leaving the metabolic chambers and before entering the switching system. These columns (approx. 300 x 80 mm) are packed with calcium sulphate anhydrous (this compound can be obtained from any reagent supplier; it is sold in granule form and can be regenerated by desiccation at 200C -225C).
4. O2 and CO2 analyser This gas analyser contains infrared CO2 sensor and a paramagnetic O2 detector fed from a damped microvacuum sampling pump. CO2 SENSOR | | Type: | Infrared, optical | | Range: | 0-10% CO2 | | Output: | linear, 0-1V (0-10% CO2) | | Resolution: | 0.1% CO2 | | Linearity: | 0.1% CO2 | | Drift: | 0.1% CO2 over 8 hours | | Response time: | 120ms (100ml/min) | | Temp coeff: | zero:<0.01% CO2 / C
span: <0.02% CO2 / C |
O2 SENSOR | | Type: | paramagnetic,
dumbell system | | Range: | 0-100% O2 | | Output: | linear, 0-1V (0-100% O2)
directly proportional to
atmospheric pressure | | Linearity: | 0.2% O2 | | Drift: | 0.01% O2 / hr | | Response time: | <0.5s (100ml/min) | | Temp coeff: | zero: 0.05% O2 / C
span: 0.25% O2 / C |
5. Recording and Analysing Unit PowerLab / 8SP is a high performance, 16 bit precision, data recording unit with 8 channels, capable to recording from slow to fast speeds (up to 200.000 samples per second continuously to disk). USB and SCSI communication for Windows and Macintosh computers. High-pass, low-pass and anti-aliasing filters.
| 
