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.