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Examples of Typical Test Engineering
Design Engagements
This
section describes some typical projects that we have been involved with
in the past. The examples include the background, what was done to
assist the project and the results.
Examples
of Projects
Glucose
Meter Tester – Electronic Strip Simulation
Situation
Client
was a startup Glucose Meter Medical company. The engineering department
put together an NI based system to use a stimulation profile to create
a “near perfect” precision electronic glucose strip simulator.
The
clients design had failed to follow FDA requirements in designing,
building and calibrating the test simulator. APD created an model of
this tester that met FDA requirements.
The final test system was
very costly and hard to program. APD proposed creating a System
Functional level tester that was much less expensive. A number of these
units were required for production test.
Tasks
Performed
APD
designed a reliable, easy to calibrate tester created to FDA
requirements, and costing less than 1/8 the cost of the original tester.
Initially
APD provided six such units for use as testers. The company didn’t want
to build the large number of these units required for various testing
requirements and production test. APD then contracted to build these
testers in batch quantities, to be purchased as needed by the client.
Results
APD
has provided over 200 of these units that have tested more than 1
million units cost effectively on the production line. They are also
used in engineering test and quality testing over several generations
of the company’s products.
Trocar
Tester - Medical Device
Situation
Client
was a Mechanical Engineering firm with a contract from a medical device
manufacturer. Need was for a device to test the Trocar spring trip
mechanism that included measuring the force as a function of spring
travel in the mechanism. The peak force needed to be measured, and
compared with a tolerance.
Tasks
Performed
The
ME firm designed the mechanical portion of the tester. APD selected the
PLC (Programmable Logic Controller) and Stepper Motor Driver used in
the design. The stepper motor turned a worm screw that compressed the
Trocar spring. A sensor fed back force data to the PLC.
APD
programmed the PLC in the Extended BASIC language that had advanced
higher level commands to control the stepper motor and monitor the
force signals. A “Go-No Go” lamp was lit after the completion of the
test. The data was also stored for later quality analysis.
Results
The
tester had
dual uses. It was used in the engineering lab and QA to measure spring
and spring trip parameter drift and to create the formal production
test program parameters.
The
unit was then used on the production line to sample test the quality of
the units being manufactured.
Medical
Device Inhaler Tester – Electro Mechanical, Optical
Situation
A
medical company hired APD to work with them to create a tester to
measure the parameters of an inhaler device that delivered a drug
orally to the patient.
The problem was to measure the density
and relative particle size of the mist generated by the inhaler device.
This would be used to check the quality of the manufactured inhalers on
the production line.
Tasks
Performed
The
tester utilized measurement of optical parameters with Laser Diode
emitters that passed light through the mist at different angles and on
to three photodetectors.
The device manufacturer hired an
optical-mechanical firm to design the optical portion of the system.
APD created the balance of the system. This included the custom
electronics to make the analog interface with a Microcontroller Unit
(MCU) Single Board computer. This created a standalone tester to be
used in final test in manufacturing.
The device could also be
used in engineering development for design test purposes, and for
setting tolerance parameters for manufacturing. In manufacturing, the
tester was used to sample test the production output, “show Go-No go”
conditions and store data for later analysis.
Results
The
tester was successfully used in the engineering lab and on the
production line. It accurately tested about 100 units per hour, and
provided valuable information to verify spring and other mechanical
parameter drift and production yield data.
Special
Purpose Analog IC Tester
Situation
Client
was an IC Semiconductor Startup company that was designing a single
chip solution for a single input voltage, 5 output voltage set of buck
and boost low noise, high accuracy, Voltage Regulators along with their
companion power management.
They needed a reasonably small tester
for this IC. It needed voltage and current measurements, along with
controlled power supply loads for the multiple outputs. The entire unit
was controlled by a self-contained Microcontroller unit.
Tasks
Performed
APD
contributed the design of the Analog portions of this tester. This
included the analog measurement system along with multiple FET switches
and relay arrays to permit all of the current and voltages to be
monitored, along with the controlled multiple electronic voltage loads.
Results
Tester
was used for engineering development of the IC, and for lower volume
lab testing of prototype and Beta units. The actual test took about 10
seconds to test a number of complex test profiles that were later used
to perform production test and validate performance.
High
Accuracy Continuity Tester
Situation
Client
was manufacturer in a production environment for large systems. They
required a detection of continuity in installed cables and assembled
PCBs. What is required is a simple method to determine if there are
continuities in various parts of the circuits without damaging the
system under test. Depending on the standard testers available, most
are unable to detect continuity under 1 ohm accurately. Sometimes this
is insufficient to determine appropriate continuity in the system and
PCB interconnects.
Tasks
Performed
APD
designed a circuit that detects open circuits above 20 ohms, and
continuity between 0.01 and 10 ohms accurately, while keeping the
terminal voltages under 100 mv during low resistance measurements. This
prevents turning on semiconductor junctions and damaging them.
Results
The
tester was made to operate as a front end of a larger test system, and
also a hand held instrument for use in large system production testing.
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