In this report only rotary torque sensor , Conducting Polymer (CP) and Quartz Crystal Microbalance (QCM) will be examined, as they are well researched, documented and established as important element for various types of machine olfaction devices. The application, where the proposed device will be trained on to analyse, will greatly influence the choice of sensor.The response of the sensor is a two part process [3]: The vapour pressure of the analyte usually dictates how many molecules are present in the gas phase and consequently how many of them will be at the sensor(s). When the gas-phase molecules are at the sensor(s), these molecules need to be able to react with the sensor(s) in order to produce a response.Sensors types used in any machine olfaction device can be mass transducers e.g. QMB "Quartz microbalance" or chemoresistors i.e. based on metal- oxide or conducting polymers. In some cases, arrays may contain both of the above two types of sensors [4]. S Beam Stainless Steel Tension and Compression Load Cell for Crane Scale 50kg 200kg 2000kg (B317MD) Read more Contact us點擊圖片放大 +2 S Type Tension Load Cell with threaded holesMetal-Oxide SemiconductorsThese sensors were originally produced in Japan in the 1960s and used in "gas alarm" devices.reaction torque sensor have been used more extensively in electronic nose instruments and are widely available commercially [1].MOS are made of a ceramic element heated by a heating wire and coated by a semiconducting film. They can sense gases by monitoring changes in the conductance during the interaction of a chemically sensitive material with molecules that need to be detected in the gas phase. Out of many MOS, the material which has been experimented with the most is tin dioxide (SnO2) - this is because of its stability and sensitivity at lower temperatures. Different types of MOS may include oxides of tin, zinc, titanium, tungsten, and iridium, doped with a noble metal catalyst such as platinum or palladium.MOS are subdivided into two types [4]: Thick Film and Thin FilmLimitation of Thick Film MOS: Less sensitive (poor selectivity), it require a longer time to stabilize, higher power consumption. This type of MOS is easier to produce and therefore, cost less to purchase.Limitation of ring load cell: unstable, difficult to produce and therefore, more expensive to purchase. On the other hand, it has much higher sensitivity, and much lower power consumption than the thick film MOS device.http://www.bransloadcell.com/
