The Microflown element is used in several standard products. One or more Microflowns are combined with an optional pressure microphone. The Scanning probe uses only a single Microflown element, ½” PU probe consists of a Microflown and a 1/10” pressure element and is packaged in a
½” package that has a gain of roughly 10dB, ½” mini PU probe is similar to the ½” probe but it is made smaller, the pu match is the smallest PU probe and the USP consists of three orthogonally placed Microflowns and a pressure element.

The standard probes are the probes that are sold most frequently.
All probes are checked and calibrated when they leave Microflown Technlogies.
All probes are sold complete, so ready to use; cabling, signal conditioning etc. is included.
All sensor configurations, orientations, cable lengths, connectors, preamplifiers can be changed on request.

USP	USP MINI	USP MATCH
PU REGULAR	PU MINI	PU MATCH
SCANNING PROBE

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Arrays of sensors are more than only a number of individual probes mounted together.
Apart from the acquisition, an array application solution consists of a three basic elements:

1. The particular sensor used.

2. The method of positioning the sensors.

3. The electrical connections.

1. The particular sensor used
The PU-mini , PU-match and the USP-mini are used in array configurations most often.

2. The method of position the sensors
There are numerous methods to configure an array of sensors. The probes can be mounted in a grid so that handheld array is created, it is also possible to put them on a surface as is done in source path contribution methods. Some solutions are listed below:

	PU match array
	USP mini array
	Hand Held array
	Free grid configuration

3. The electrical connections
Obviously, the number of cables and connectors increase if a lot of sensors are used. The change of making mistakes, mixups and set up time increase with that. To minimize this, Microflown technologies designes therefore special preamplifiers, multipin conmnectors and BNC breakout boxes that go to the dedicated frontends (24channel, 96channel).

Microflowns can be calibrated in several ways. Two methods are standard nowadays:

The small standing wave tube Can be used in a 20Hz-3.5kHz bandwidth and is simple to use: one needs to use one equation to obtain the calibration data. The method is not affected by background noise.

The piston on a sphere calibration technique It is a free field method that requires some space. The method works in the full acoustic bandwidth. The method requires some software to operate.

A monopole sound source is used for reciprocal measurements in vehicles. It is an omni-directional volume velocity sound source. The source has a particle velocity reference sensor so the output can be measured.

The sound power output of a monopole source is proportional with the frequency squared.
The sound pressure at one meter therefore low at low frequencies.
To be able to reach relative high sound pressure at low frequencies with an acceptable source velocity one needs to increase the source diameter. For an omni directional behaviour however, the diameter should be small compared to the wavelength Because of that contradiction two monopole sources are designed. The low frequency monopole with a source diameter of 12cm and a high frequency monopole with a source diameter of 12mm. A head shaped sound source is developed to be able to calculate what a Human would hear.

	The low frequency monopole 30Hz-300Hz
	The high frequency monopole 100Hz-6kHz
	Head shaped source (100Hz-6kHz)