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[IP] IR-1000 Precision

The IR-1000 uses a precision DC motor, similar to those used in 
medical and scientific instruments.  For example, catheters, surgical 
hand instruments and surgical robotics utilize DC motors as the motor 
of choice as it provides advantages in size, power, efficiency and 
accuracy over the alternatives.

The IR-1000 pump is built with layer upon layer of redundant safety 
features, designed and tested to very stringent quality criteria. 
The DC motor incorporates a gear reducer and an encoder to measure 
motor shaft movement drives the pump.  The motor has a magnetic 
encoder with ten pulses per revolution.  By counting the rising and 
falling edges of these pulses, if it possible to resolve every 18 
degrees of motor rotation.  The 18 degree rotation is reduced by the 
gear reducer to approximately a 17.6 millidegree (one thousandth of a 
degree) rotation of the lead screw, which in turn drives the plunger 
1.5 microinches (one millionth of an inch).  This motion causes 0.45 
milliunits (one-thousandth of a unit) of U-100 insulin to be 

The pump delivers insulin every three minutes, regardless of the 
basal  rate (unless it is zero).  For example, if the basal rate is 
set for 0.15 units per hour, the pump delivers 7.5 milliunits every 
three minutes.  When a particular basal rate is set, the basal rate 
is stored into the memory.  An external clock wakes the 
microprocessor every three minutes, at which time the microprocessor 
runs a series of self-tests to confirm that all pump functions are 
working properly.  Providing the pump passes the self-tests, the 
microprocessor then checks the memory to find the current basal rate. 
It hen looks up in a look-up table the number of units that should be 
delivered and the numbers of encoder pulses that the counter should 
count to deliver the appropriate amount.  The microprocessor then 
commands the electronics to supply a pulse of DC voltage to the motor 
to allow it to turn.  The encoder counter counts the number of 
encoder pulses and the DC voltage is turned off when the counter 
counts the appropriate number of encoder pulses.  Precise delivery, 
incomparable safety!

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