Ultrasonic sensors provide key safety feature for infusion pumps
Infusion pump is that accurately
dispenses medication and fluids, such as morphine and nutrition, into a
patient’s circulatory system. A key safety
feature of the pump is an ‘air-in-line’ detection system, which
monitors for the presence of air bubbles in the fluid.
“Accurate detection of air bubbles is vital in maintaining the health
and recovery of patients, Air embolisms can lead to serious complications in blood flow and the
heart’s operation.”
There are other technologies that are used to detect air bubbles such
as infrared. However, ultrasonic technology
provides the most accurate and reliable detection. 
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How Ultrasonic Sensors Work
Ultrasonic sensors depend on two separate devices:
an ultrasonic transducer and a detector. An ultrasonic transducer is any
device that converts energy into an ultrasonic frequency. Though dog
whistles and several other devices can convert mechanical energy into an
ultrasonic frequency, ultrasonic transducers are usually made from
piezoelectric crystals that can change size when a voltage is applied to
them. When an alternating current is applied to a piezoelectric
crystal, it vibrates extremely fast and produces an ultrasonic sound
wave. The detector is also made of a piezoelectric crystal, but produces
a voltage when an ultrasonic frequency comes in contact with it,
effectively producing the opposite results. A sensor calculates the time
that it takes in between broadcasting the ultrasonic frequency and
receiving the incoming waves.
How to detect air in line
If there is fluid in the infusion line between the sensors
then a signal is received, but when air passes through a reduced signal
is received. This change in signal generates an alarm, alerting the user
that an air gap is present, and the pump automatically stops infusion.
