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.
List of Typical Past Projects
Glucose Meter Tester – Electronic Strip Simulator
Trocar Tester – Medical Device
Medical Device Inhaler Tester – Electro Mechanical, Optical
Special Purpose Analog IC Tester
High Accuracy Continuity Tester
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.