The USI thermal flow sensor chip
uses a solid-state design, thus eliminating the need for a cavity or
membrane either on the surface or inside (Figure 1). The Die’s contact
surface is coated with a thin-film material that was first developed for
NASA’s space applications. This proprietary coating is hard (its
hardness is second only to diamond), smooth, non-stick, and corrosion
resistant. The solid-state design and the advanced coating of the MEMS
Die allow the flow sensor to withstand high pressure, intense vibration,
and impact from particles in the liquid medium. Temperature differences
are directly related to flow rates, the USI thermal flow sensor chip
provides highly linear output signal. Figure 2 shows that the sensor
provides a highly linear output curve for flow rates as low as 10 mL/min
and as high as 180 mL/min, using 2D diesel as the flow medium.
Figure 2 USI Thermal Flow Sensor Provides Highly Linear
The MEMS Die also allows a
packaged module to be easily cleaned by simpy flushing cleaning solution
through the capillary tubing.
Performance specification of the flow sensor module.
||±3% Full Scale
||±0.2% Full Scale
||0 to 70 ºC
||Max 60 psi
||±3% Full Scale
USIs liquid flow meter is suitable for a wide variety of
industrial and commercial applications such as fuel consumption
measurement for engines and generators, control of refrigerant flow in
air conditioners and refrigerators, and generalpurpose liquid flow
control in industrial processing.
Typical Package Description
The USI custom liquid flow meter consists of a flow
sensor module that is based on the thermal mass flow principle; A
display module that shows flow rate and cumulative volume, buffers the
data, and provides an interface for data extraction, and a casing that
houses both the flow sensor and the display modules.
Figure 3 Flow Sensor Module (The capillary casing also
contains signal conditional circuitry)
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