Measure blood flow in vessels as small as 0.8 mm Monitor up to 6 vessels simultaneously Determine blood flow velocity through extracorporeal
cannulae Measure blood flow in vessels as small as 0.8 mm Monitor up to 6 vessels simultaneously Determine blood flow velocity through extracorporeal
cannulae 
The Triton Technology Model 202 Pulsed Doppler Flowmeter Module is a precision
instrument designed to measure blood flow velocity in experimental preparations. As a
member of the SYSTEM 6 Modular Physiological Instrumentation family, it operates
individually or in conjunction with other instruments when housed in the SYSTEM 6
mainframe. The Pulsed Doppler Flow Module is a state-of-the-art system for measuring
blood
flow velocity. The low-mass, inexpensive transducers are ideal for long term,
chronic
implantation, particularly when compared to the bulky, heavy transducers
required for
other technologies. These transducers use lightweight, non-shielded
PVC-insulated wire.
Blood flow velocity is measured by projecting bursts of high frequency ultrasound
diagonally across the blood vessel. Sound is backscattered from blood cells and the
frequency of the scattered sound is shifted in proportion to the velocity of the cells.
The
scattered signal is detected and a voltage proportional to the velocity of the blood
flow is
developed for recording. A variable range gate control allows the user to measure
blood
flow velocity at many points across a blood vessel.
This module incorporates a number of unique features not found in other designs: A
patented noise reduction circuit, Dynamic Noise Reduction, improves the signal-to-noise
ratio by as much as 10 dB compared to other pulsed Doppler flowmeter designs. Range
information is presented on the System 6 Mainframe front panel LED display in 0.5 mm
increments and as a proportional DC voltage at the back panel. The instantaneous flow
velocity and direction sense is displayed on a dynamic LED bar graph display also on
the
System 6 Mainframe front panel.
The most unique feature of the Model 202 is its internal calibration circuitry. The
calibration is a true end-to-end calibration using a family of frequencies developed from
the main quartz crystal clock. These stable, accurate frequencies are determined from the
Doppler equation, the
operating frequency and the transducer geometry. Other commercial
pulsed Doppler designs utilize a simple voltage
divider across the power supply as a
calibration.
The pulsed Doppler Flow Module is available in 20 and 10 MHz versions for use on small
and medium blood
vessels. Many different implantable transducers
are available to suit specific applications.
DNR is a registered trademark of National Semiconductor
Copyright 1995 Triton Technology, Inc.
Updated March 28, 2006