ECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Assignment#01: Literature Survey on Sensors and
Actuators Actuators
Topic: Air Bubble Sensors/Piezoelectric Nanoactuators
Prepared by:Nathan Sorensen
Utah State University3/11/2005
Air Bubble Sensors Outline – Reference list– To probe further– Major applications– Basic working principle illustrated– A typical sample configuration in application
(application notes)– Major specifications– Limitations– And many more relevant issues in applications
(such as, how to choose, cost information, where to buy etc.)
Reference list
• www.introtek.com• www.e-t-a.com• http://www.zevex.com/appliedtechnology/ultraso
nics.cfm• www.eidusa.com• www.consense.com• http://www.yamatakeusa.com/photo_electric_gui
de.htm• www.murata.com/catalog/p19/p19_04e.pdf
To explore further (survival pointers of web references
etc) Do’s• Identify the exact purpose of the sensor. (Often level
sensors are also bubble sensors)• Identify the type of tubing or pipe to be used with the
device.Don’ts • Don’t assume that just because a sensor detects
bubbles that it can detect all sizes of bubbles.• Don’t assume that a sensor is used for all sensing
mediums• Don’t settle without comparing all the different types of
sensor options for a specific application.
Air Bubble Sensors
Finding the Needle in the Haystack
Major applications
What would be the use of a bubble sensor?• Detect anomalous bubbles in high
precision chemical processes.• Enable precise measurement of fluid flow.• Protect medical patients from embolisms
due to air being introduced through IV lines into the blood stream.
• Determine fluid flow rate.
Sensing Methods
Invasive• Sensors designed to come in contact with
the fluid medium.• Methods for invasive sensing include:
– Photoelectric– Fiber Optical Strands– Conductivity– Ultrasonic– IR
Sensing Methods
Non-Invasive• No contact with the fluid being transferred• Non-Invasive sensing methods include:
– Ultrasonic– IR– Capacitive
Invasive vs. Non-Invasive
Is there a drawback to which type is chosen?• Invasive sensors are exposed to the fluid being
transmitted and so are limited in two respects:– The sensor must not be reactive with the fluid to be
transferred through it.– The fluid must not inhibit the sensors activity by
particulate collection over time. • The longevity of the sensor requires that it not
be broken down over time.
Invasive vs. Non-InvasiveDo Non-Invasive sensors
have any similar drawbacks to Invasive?
• Particulate accumulation on the wall can decrease sensor accuracy.
• The transport medium must be able to be sensed through
Copyright © 1996-2005 Erlich Industrial Development, Corp. (EID, CORP) ALL RIGHTS RESERVED.
INTERFACER-AILS FeaturesAir in line output multi-turn trimmer adjustment. Power via 5VDC. Converts Air in line (via light) to CMOS or TTL voltage level. Convert switch to voltage CMOS or TTL levels. Can be customized to accommodate your input voltage requirement. On board trimmer facilitates precise calibration of air detection sensitivity. Specifications
Output voltage 5V, 0.2VDC PCB material FR4
Switch Input Filter B.P.F. 2Hz-1KHz Storage temperature 40 - 70 [F] Operating temperature 32 - 140 [F](0to 60°C) @
95% RH Low board DC voltage 9 [V]
Powersource 5VDC +/-5%, Adjustment Via trimmer for air detection sensitivity Mounting Two 0.125” holes Manufacture 100% in USA
Sensor Selection Guide
Important Aspects to Consider:• Type of fluid• Type of tubing or pipe used to transport
fluid• Required precision • Ease of integration into design or existing
system.• Cost
Ultrasonic Bubble Sensors• By far the most prevalent
bubble sensing method.• Uses piezoelectric materials
to create ultrasonic waves• Two main types:
– Continuous: transmits a continuous ultrasonic wave and detects the drop in wave amplitude through air.
– Pulsed Wave: transmits a pulsed wave and then detects both the amplitude and duration of the received wave to determine the medium.
Pulsed Wave vs. Continuous• Pulsed Wave are more
precise using time delay and amplitude to determine medium
• Pulsed Wave require microcontrollers and special calibration
• Continuous are far cheaper and simpler
• Continuous give analog outputs
Advantages vs. DisadvantagesAdvantages• Non-Invasive ultrasonic wave used for bubble
detection• Highly Precise: straight line of sight between
transmitter and receiver• Particulate accumulation will not effect bubble
detection• Can be used with any tubing typeDisadvantages• Piezoelectric ceramics are expensive
IR or Photoelectric Bubble Sensors
• Can be invasive or non-invasive• Uses the timing delay from pulsed
light beam passed through medium to detect bubbles
• Widely used in medical applications
Yamatake Sensing Control, Limited. ©
Copyright 2004
Advantages and DisadvantagesAdvantages• Simple to integrate into
existing systems. • Well developed sensor
technology• CheapDisadvantages• Particulate accumulation
lowers accuracy over time• Non-Invasive type requires
transparent or translucent tube material
• Invasive type is exposed to fluid
Copyright © 1996-2005 Erlich Industrial Development, Corp. (EID, CORP) ALL RIGHTS RESERVED.
Capacitive Bubble Sensor
• Non-Invasive Sensor• Uses the capacitance
of the medium to detect the presence of air in the line
Advantages and DisadvantagesAdvantages• Non-invasive• Capacitance is not affected by particulate
accumulation on tube or pipe• Tube or Pipe can be any materialDisadvantages• Small bubbles are not easily detectable.• Must be calibrated to the specific tubing material• Cost
Fiber Optical Strand Bubble Sensors
• Invasive• Detects fluid or air by
the amount of light refracted at the sensor tip
• Sensor made of glass or other materials that transmit light
Catalog Listings/ Specifications
HPF-D033 HPF-D027
Diameter 4 mm 6 mm Bend Radius 30 mm 40 mm
Operation Temperature -30 to 105°C -30 to 105°
Advantages vs. Disadvantages
Advantages• Quick response time• Glass and other such materials are very
resilient to most fluids.Disadvantages• Particulate accumulation at the tip causes
significant sensor error• Difficult to integrate into systems
Where do I buy them?
• Bubble sensors are a rather specific sensor so most of the sensor are sold directly by the manufacturer.
• Manufactures will also calibrate sensors to ensure their accuracy in your particular need.
• Any questions about purchasing items must be directed to the manufactures.