Sensors & Transducers e-Digest (S&T)
No. 3, March 2001
Electronic Acoustical Sniffer
In just 10 seconds, a new type of electronic nose can quantitatively separate, identify, and measure the chemistry of any fragrance, odor, vapor, or smell with part-per-billion accuracy. And, it even creates a picture of its findings!
zNose, designed by Electronic Sensor Technology (EST) of Newbury Park, CA, was initially developed for sniffing out drugs, explosives, and pollution in air, water, and soil. Its primary use, however, is by the food, beverage, and cosmetics industry to measure quality and to sniff out contaminants. Recent applications include measuring fatty acids in milk and soymilk, freshness in fruit juices, and odors in vitamins. The wine industry uses zNose to detect trichloroanisole, a flavor-destroying chemical that results from moldy corks.
Unlike conventional and less accurate eNoses that are based on non-specific sensor arrays, zNose uses fast chromatography to separate chemicals according to their chemical and physical makeup. A single acoustic wave resonator produces hundreds of independent, virtual sensors that detect and measure the concentration of each chemical. Results are interpreted by software and displayed as a "vapor print™" that can be read easily by humans.
Visit EST's Web site for a technical description of how the zNose works.
SoftNoze Announces the Largest Offering of Sensor Accessories
SoftNoze, a rapidly growing manufacturer located in upstate New York, announces the release of the worlds largest offering of sensor accessories. In addition to new models of the original and patented Cushioned Sensor Mounts, the 32-page color catalog offers over 20 different product categories. When combined with "SoftNoze CPR", engineers and technicians applying industrial sensors now have a single source for mounting brackets and ancillary components.
The catalog provides "off-the-shelf" solutions for inductive, capacitive, laser, photoelectric, ultrasonic, fiber-optic, transducers, thermocouples and more which makes 'system design & build' faster and more economical. Groundbreaking solutions include; Clamp-style Universal Brackets (CUB(tm)) and the Sensor Mounting System (SMS(tm)) which allow unlimited mounting and aiming of photoelectric sensors- all models and sizes.
Another patent-pending solution contained in the catalog is the Proxtrol(tm) Limit Switch (PLS) line. PLS models are standard limit switch body, which accept standard 12mm inductive proximity sensors resulting in PLC-friendly, solid state, limit switches.
Should designers not see what their application requires, they can submit the SoftNoze Custom Product Request (CPR) form. SoftNoze will professionally manage and use cutting edge technologies to develop, present and delivery sensor accessory solutions.
Rotation Speed Sensors (Part II)
1.3 Piezoelectric Sensor
The piezoelectric sensor is a type of electromechanical sensor. The piezoresonator is based on piezoelectric cell of the regular shape (rectangular plate, disk, rod, etc.) made from crystalline or piezoelectric material. The operation of the piezoelectric resonator is based on piezoelectric effect that consists of transformation of input voltage into mechanical stress inside the piezoelectric cell (reversive piezoelectric effect), and response - charges on electrodes because of piezoelectric cell deflection under effect of mechanical stress.
The piezoelectric rotation speed sensor is shown in figure. 1. The constant magnet 2 is build-in into encoder 1. The piezoelectric cell 4 is anchored on the same radius in sensor's box 3. The magnet conduction plate 5 is pasted on the piezoelectric cell 4.
Figure 1. Piezoelectric transducer
1 – encoder; 2 – constant magnet; 3 – sensor's box 4 – piezoelectric cell; 5 – magnet conduction plate, 6-amplifier, 7- pulse shaper, 8-microcontroller
At encoder rotation the permanent magnet is moving near the plate. The plate is attracting by the magnet, deforming the piezoelectric cell. The voltage pulses on the piezoelectric cell after amplification and shaping are counted by microcontroller. The number of pulses is proportional to the rotation speed.
(To be continued)
Author: Vadim P.Deynega
State University Lviv Polytechnic,
Department of Automation,
Lviv, UA, 79013
A new book: Integrated Converters
D to A and A to D Architectures, Analysis,
Paul G. A. Jesper
Analog to digital and digital to analog converters are essential interfaces between computers and the outside world. They link sensors to signal processing devices and are embedded in an ever larger number of integrated circuits used for example in the telecommunications industry, remote control devices, and medical electronic instruments.
This book surveys recent progress and gives an account of the working principles of integrated converters. It describes the architectures and discusses accuracy and speed in depth.
For more details about this book click here
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