CONTENTS

An instrument for measuring the velocity

of flow of a fluid (as blood) in a tube or pipe

Blood flow is a time varying quantity and

important parameter to be

measured

Need For Blood Flowmeter ?

Provides vital info about the

oxygen and nutrients to

various parts of the body

The average velocities of

blood flow vary over a wide

range depending on diameter of blood vessel.

Inspection for block in blood

flow.

Testing artificial blood vessels during organ

transplantation.

Measurement Techniques

Electromagnetic Blood Flow meter

Ultrasonic Blood Flow Meter

Laser Doppler Blood Flow Meter

1.Electromagnetic Blood Flow Meter

Works based on the principle ofelectromagnetic induction

“The voltage induced in a conductormoving in a magnetic field isproportional to the velocity of theconductor”

The conductive blood is the movingconductor

It is invasive technique

Principle Diagram

Electromagnetic Blood Flow Meter

Electromagnetic Blood Flow Meter

A permanent magnet or electromagnet positioned around the blood vessel generates a magnetic field perpendicular to the direction of the flow of the blood.

Voltage induced in the moving blood column is measured with stationary electrodes located on opposite sides of the blood vessel and perpendicular to the direction of the magnetic field.

This method requires that the blood vessel be exposed so that the flow head or the measuring probe can be put across it.

2.Ultrasonic Blood Flow Meter(principle)

Ultrasonic waves are ideal for non-invasive

sensing

A moving blood cell changes the frequency of sonic waves before

and after it.

The sonic waves compress before an

object and spread out behind it.

This frequency shift is the Doppler Effect

Ultrasonic Blood Flow Meter

These devices include a transmitter and receiver.

Reflective material bounces the transmitted wave back into the receiver.

The received wave has a frequency shift. The source frequency is lowered twice.

The first shift occurs when the transmitted wave hits the object and the second shift

occurs when the resulting wave comes back .

Ultrasonic Blood Flow Meter

3.Laser Doppler Blood Flow Meter

Principle of laser Doppler Flowmetry

Red light is emitted from a light source; if the light beam is scattered-off of stationary tissue or cells, there is no shift in the light spectrum. If, however, the light hits a moving cell in a blood vessel there is a shift in the light spectrum of the scattered light according to the Doppler flowmetry

American National Standards Institute (ANSI) Definition

o A device which provides a usable output in response to a specified

measured input.

A sensor acquires a physical parameter and converts it into a signal suitable

for processing (e.g. optical, electrical, mechanical)

Physical Quantity

sensorElectrical Quantity

Flexible Sensors(New Technology)

University of Illinois at Urbana-

Champaign has developed a

flexible electronic sensor that

can measure blood flow on top

of the skin or, can possibly be

implanted onto the tissues

themselves

Flexible sensor that can

stick onto the skin like a

temporary tatooo

Flexible sensor

The devices are made from a thin array of metallic wires that are oriented around a central sensor and map blood flow as well as pick up on the slight temperature increase that each pulse of blood brings

They are coated in a thin layer of silicone, so they are flexible and can stick to the skin like temporary tattoos

Can determine temprature to the third decimal place and accurately track the change at that level, it provides a lot of deep insight into physiological health

Could potentially be used for lie detector

Blood Flow Measurement Devices Market, by Applications

Gastroenterology

Diabetes Research

Dermatology

Peripheral Vascular Diseases

Heart attack