Custom Test Systems for Medical Device Industry – Viewpoint Systems2019-08-05T09:51:33-04:00

Test System Development for the Medical Device industry

  • Platinum-level National Instruments Alliance Partner, putting us in the top 2% worldwide

You’re cautious and risk-averse because  you need to worry about things like 21 CFR Part 820 and Part 11.  You need to dot your i’s and cross your t’s.

We understand.

Our expertise in the medical device industry focuses on test system development.

How we can help: our capabilities & expertise

  • Familiar with 21 CFR Part 820 and Part 11

  • Support V&V effort during IQ & OQ

  • Interface to Part 11 compliant databases for testing procedures and measurement results

  • User access management
  • Test sequence release management

  • Deep expertise with PXI-based system development – Over 1,500 PXI projects completed, across multiple industries

  • Verification of test sequence content & content of test results

  • Test report creation and management

Want more proof points?  Check out these medical device test case studies:

Custom Endurance Test System – for a medical device

Custom Endurance Test System – for a medical device

Increased level of automation allows for multi-day and multi-week test runs

Client

A medical device manufacturer

Challenge

Our client wanted to improve the endurance testing of an implantable medical device product to help determine the recommended lifetime of the product. An obsolete test system existed, but the client wanted improved performance, UX and configurability. They wanted to just hit the “go” button and let it run for days or weeks. They also needed to be able to have new features added after the first release.

Solution

The custom product validation endurance test system utilizes NI cDAQ off-the-shelf hardware combined with custom LabVIEW-based software to provide automated N-up endurance testing of the UUT.

Benefits

  • Higher fidelity DAQ
  • Increased configurability of the system to run tests the way the client wants to
  • Increased level of automation allows for multi-day and multi-week test runs.

System Overview

The endurance tester physically stresses the UUT to measure force and eventually breakage events. These events are used to help determine the recommended lifetime of the product. The tester tests multiple UUTs in parallel in order to gather more data faster for statistical validity. The system collects data until all UUTs break or the operator stops the test.

Viewpoint provided the software and advised DAQ hardware selection. The rest of the test system hardware was selected and assembled by the client.

The automated test system applies a varying cyclical force to multiple UUTs while measuring the force applied to the device. The software automates the data acquisition, analysis, load application, and motor during a test. The system measures all forces applied simultaneously while synchronizing that data to a cycle counter. That data is analyzed to determine average, maximum, and minimum force applied to the device over a user configurable number of cycles.

While running there are multiple alarm states that are monitored. When these alarm states occur, a file can be generated to dump a user configurable duration of force measurements to a file. Other alarms generated trigger the system to change a digital output state triggering a text message to be sent to the operators of the system. The system was designed to test for weeks at a time.

SOFTWARE FUNCTIONS
Test Sequencer
UI
Data Logging
Report Generation
Breakage Event Detection
HARDWARE USED
NI cDAQ
Multiple NI load cell cSeries modules
NI cSeries Digital Input module
NI cSeries Digital Output module

Custom Test System Using NI PXI for Electrical Test

Custom Test System Using NI PXI for Electrical Test

Updating an obsolete tester that maintains functionality

Client – Medical Device Manufacturer

Challenge

Our client already had a test system in place, but the tester (really two test systems testing two different product variants) was becoming obsolete.  The tester was old, hardware was failing, and it was getting harder and harder to keep it reliably running.  They wanted a new tester to improve reliability, but maintain the functionality of the existing tester to keep the FDA-mandated verification and validation time to a minimum.

Solution

The updated end-of-line manufacturing test system maintains the functionality of the old test systems, but with updated hardware and software.  The same software is utilized for both the manual test system update and the automated test system update.  Our client deployed 6 manual testers and 1 automated tester.

Benefits

  • Improved maintainability and reliability with updated hardware and software
  • Maintains existing test system functionality to keep certification time down

System Overview

There were two variants of the new test system.  One was for an older product line that utilized manual test, with an operator that connected/disconnected the UUT, and initiated the test.  The other was an automated tester, integrated into a manufacturing machine.  Both testers utilized custom fixtures (provided by the client), off-the-shelf NI measurement hardware (selected by Viewpoint), and custom test software (developed by Viewpoint).  The software is configurable for both the manual test system and the automated test system.

SOFTWARE FUNCTIONS
Read UUT limits from config file
Perform tester self-test
Measure impedance
Power UUT
Pressurize UUT
Measure UUT output
Perform leak down pressure test
PLC interface (for automated tester) for start, done, pass, fail
HARDWARE USED
Custom test fixture (provided by client)
NI PXI
PXI Multifunction I/O Module
PXI Digital I/O Module
PXI Relay Module
PXI Digital Multimeter Module
PXI Switch Matrix Module

*- images are conceptual, not actual

Automated Manufacturing Test System for Electronic Medical Devices

Automated Manufacturing Test System for Electronic Medical Devices

Using PXI and LabVIEW for modular testing of over 1,000 different models

Client – a medical device manufacturer and repair depot

Challenge

Our client manufactures hospital patient pendants used to control bed frame, nurse calling, and TV functions. The company was also growing after adapting a business model of being a repair depot for older designs for their own and the pendants of other manufacturers. As such, their products are very high mix and medium volume.

The basic functions for all these pendant models are closely related, so the client wanted a means to build a single automated test system that could verify functionality for 1000s of models. And, since the products are medical devices, the testers needed to comply to 21 CFR Part 820 and Part 11.

Solution

The testers were designed to support the common measurements needed to test the circuitry of the devices as well as the complex signals required to drive TVs and entertainment systems. A test sequence editor was created which allowed the client to create as many test sequences as needed to test each specific pendant model by creating a list from pre-defined basic measurement steps configured for each specific measurement.

For example, each device had a power supply, the voltage of which needed to be tested. To test a specific model, a voltage measurement step was added to the model-specific sequence and configured with the upper and lower measurement limits for the power supply. The complete test sequence was created by adding and configuring other measurements test steps as needed. Each test step could also be configured with switch configurations to connect the measurement equipment, such as a DMM, to the proper pins on the device circuit board.

Using this configuration process, the client was able to support the testing of well over 1000 models without any programming. A separate application was developed to create these test sequences which were saved as XML and fed to the test system for selection and execution.

The test execution was managed by NI TestStand and the pre-defined common test steps were written in LabVIEW. The test sequences and test results were interfaced to the client SQL database which they used in their ERP system. This ERP system used the results produced by the test system to help manage the workflow of production, for example by assuring that all units had passed testing before being shipped. Part 11 compliance was handled through checksums used to check if results had been modified.

Benefits

  • Test sequence editor used to develop and maintain tests for 1000s of device models
  • Enabling our client to create test sequences without programming reduced overall development costs by about 50%.
  • Test sequences and test results were stored in the client’s ERP SQL-compliant database for integration with manufacturing workflow
  • Modular and common software developed for the test systems reduced the V&V effort during IQ & OQ by allowing testing of the test execution application separate from the individual test sequences.

System Overview

The automated test system was able to execute each test sequence in three different modes: engineering, service, and production. Each mode has been specifically designed for various departments throughout the manufacturing floor. Typically, the manufacturing engineer would verify the sequence by executing it in engineering mode. Once the test sequence parameters pass, it was then approved for production testing.

During actual product testing, an approved and digitally-signed test sequence is loaded and executed via the test sequencer, designed for automated production. During execution, test results are displayed to the operator and simultaneously pushed to a database. The automated test system produces a record for each tested device, indicating the disposition of each test step and the overall performance of the device. All result data are digitally signed and protected from tampering.

The architecture of the test system follows a typical client – server model.

All client stations communicate with a central ERP and SQL server and each computer is secured by applying operating system security. The SQL server contains all of the test definitions, device history records and results. Information from it can be queried at any time by quality engineers throughout the organization, assuming they have proper login access. This provides real time status about products ready for shipment. Also, other than the software running on the client stations, no other user has permission to write or modify any information in this database. The client is able to keep the server in a protected area separating it from the manufacturing environment while the client test stations are placed throughout the manufacturing area.

Surprisingly, there were only twelve test steps needed to uniquely configure and be combined to create sequences to test well over 2000 unique models. Test steps are capable of measuring basic resistance, current and voltage parameters as well as perform sound quality measurements and high speed digital waveform analysis. Several tests were designed to be subjective while others are fully automated and test to a specified acceptable tolerance. During configuration, each test step requires the manufacturing engineer to enter expected values and tolerance limits to define pass – fail status. Upon testing, the devices are attached to a generic interface connection box and the test system makes the appropriate connections and measurements.

SOFTWARE FUNCTIONS
NI TestStand
Low-level measurement drivers to interface to a DMM, signal generator, switches, and data acquisition cards.
Measurement-based test steps
Test sequence execution
Test sequence management
User access management
Test report creation and management
Verification of test sequence content and ability of user to execute
Verification of the content of the test results
HARDWARE USED
NI PXI chassis and controller
NI PXI acquisition cards for analog measurements
NI PXI acquisition cards for digital input and output
NI PXI DMM for precision voltage and resistance measurements
Audio amplifier for speaker tests
INTERFACES / PROTOCOLS
Ethernet

*- images are conceptual, not actual

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Automated Manufacturing Test Systems for Medical Diagnostic Equipment

Automated Manufacturing Test Systems for Medical Diagnostic Equipment

Using NI PXI and LabVIEW as a common architecture for multiple test systems testing several subassemblies

Client: a manufacturer of automated blood analysis machines

Challenge

Our client was embarking on a complete redesign of their flagship automated in-vitro Class 1 blood diagnostic machine. In order to meet schedule goals, the design and build of several automated test systems needed to occur in parallel with the overall machine. In a major design paradigm shift, many components of the machine were being manufactured as modular subassemblies, every one of which was an electro-mechanical device. Thus, multiple testers were required to test each of the specific subassemblies in the machine. And, since this was a medical device, the testers needed to comply to 21 CFR Part 820 and Part 11.

Solution

With a looming deadline, the testers needed a common architecture, so that all testers could leverage the development from the others. Since each subassembly could be tested independently of the overall machine prior to final assembly, the design of the testers was based on a common measurement and reporting architecture, written in LabVIEW, that interfaced to the customers Part 11 compliant database for testing procedures and measurement results. Furthermore, procedures and validation checks for calibration of the testers were part of the overall test architecture.

Benefits

  • Modularization of the test system architecture aided development and maintenance
  • Reduced overall development costs due to standardization of test sequence steps and reporting
  • Both test sequences and test results were stored in a managed database that satisfied 21 CFR Part 11 requirements
  • Modular and common software developed for the test systems reduced the V&V effort during IQ & OQ.

System Overview

Since multiple subassemblies were being tested, with one part-specific test system per part, the automated test systems used as much common hardware as possible to simplify the development effort through common hardware drivers and test steps. Measurements were made with PXI equipment. Test steps and the test executive that executed the test sequence(s) were developed using LabVIEW.

The types of test steps required to verify the proper operation of each subassembly were categorized into basic operations, such as voltage reading, pulse counting, temperature reading, and communications with on-board microcontrollers. The specifics of each measurement could be configured for each of these measurement types so that each test step accommodated the needs of the specifics of each subassembly. For example, one subassembly might have needed to run the pulse counting for 2 seconds to accumulate enough pulses for accurate RPM calculation while another subassembly might have only needed 0.5 seconds to accomplish that calculation.

The configuration of a test step algorithm was accomplished via an XML description. The accumulation of these XML descriptions of each test step defined the test sequence run on that specific subassembly.

Test results were associated with these test sequences by completing the entries initially left blank in the test sequence, so that all results were explicitly bound to the test sequence.

The operator user interface distinguished between released and unreleased test sequences. With unreleased test sequences, engineers could try the most recent subassembly designs without needing to wait for final validation. The released sequences were only available to test operators. This login-driven branching was managed using the Windows login, so that the client employees could use their company badge-driven login process. Once logged in, the user would be able to execute the test sequence in automated mode, where all steps happen automatically, or manual mode, where one step could be operated at a time.

Furthermore, the Windows environment was locked down using built-in user account group policies to designate the level at which a user could access Windows or be locked into accessing only the test application.

V&V Effort

During the V&V effort, each test sequence was verified for expected operation, against both known good and bad parts. Once verified, the sequence was validated against the requirements and, when assured to be as expected, a checksum was applied to the resulting XML test sequence file and all was saved in a Part 11 compliant database. Upon retrieval, when ready to run a test, the sequence was checked against this checksum to assure that a sequence had not been tampered.

Test results, saved as XML in the same file format as the test sequence, were also surrounded by a checksum to verify that no tampering had occurred.

The IQ/OQ efforts were handled in a traditional manner with the client developing the IQ/OQ documentation, with our assistance, and then executing these procedures, again with our assistance.

SOFTWARE FUNCTIONS
Low-level measurement drivers
Measurement-based test steps
Test sequence execution
Test sequence management
User access management
Test report creation and management
Verification of test sequence content and ability of user to execute
Verification of the content of the test results
HARDWARE USED
PXI chassis and controller
PXI acquisition cards for analog measurements
PXI acquisition cards for digital input and output
CAN card
INTERFACES / PROTOCOLS
Ethernet
CAN

*- images are conceptual, not actual

Yes, I’d like to chat about my test system needs »

Manufacturing Test – for mission-critical components

PXIe

Manufacturing Test – for mission-critical components

 

Using PXI & LabVIEW RT

Client: A major manufacturer of implantable cardiac and neural stimulators

Challenge

Our client needed several extremely reliable test systems to test the batteries that power their implantable medical devices. These new test systems were needed for two main reasons. First, the needed to upgrade existing obsolete test equipment, based on antiquated hardware and software. Second, new battery designs could not be tested on the old equipment.

A critical aspect of the new test system was the need to detect any excessive charge being extracted from the battery, thus rendering it unsuitable for surgical implantation. Thus, the test system needed to monitor the total energy withdrawn from a battery during testing to assure that it never exceeded a certain limit while also offering precise control of the type of pulses being drained from a battery.

All test results had to be stored in a database in order to maintain device history for each battery manufactured for archiving, quality control, and process improvements.

Solution

PXIe

The updated manufacturing test system is PXI-based along with a custom micro-controller-based circuit board for some low-level control. Each PXI controller communicated to the microcontroller (uC) on the custom PCB via CAN. The uC controlled the current drain from the battery while monitoring actual current and voltage from the battery at over 1000 samples per second using a precision 6.5 digit PXI DMM. Additionally, each PXI chassis was used to test many hundreds of batteries. Signal connections were handled by several switch multiplexers. Overall control of all the PXI testers was managed by a host PC connected to the PXI controller.

Benefits

  • Reduced test system cost vs complete COTS solution with combo LabVIEW RT on PXI and firmware on microcontroller-based custom circuit board
  • Enabled tight control of DUT operation on controller with microsecond level responsiveness while being supervised by higher-level PXI RT
  • Quick-reaction test abort capability
  • Test results stored to database for archiving, quality control, and process improvements

System Overview

In a simplified view, the testing proceeded by pulsing the battery with a series of different durations and varying amperages. The exact sequence of this pulsing is unique for each DUT model. Measurements were made using a PXI filled with various NI boards such as DMMs, for accuracy, and data acquisition cards, for general purpose use.

Additionally, the pulsing amperage levels needed to be tightly controlled in order to know that the tests have been performed properly. Thus, a real-time amperage control scheme had to be implemented to maintain the level requested for the pulse. We chose to accomplish this control via an analog control circuit developed using a custom Viewpoint-developed circuit board. This board was controlled via a Microchip PIC microprocessor. The LabVIEW RT application communicated with the microcontroller to setup the pulsing sequence and coordinate the start and stop of the pulsing and the NI acquisition hardware.

This custom circuitry also reduced the overall cost of the test system by about 40%.

The engineering time to design this custom circuitry was more than offset by the reduction in material costs because more than 10 test systems were deployed, allowing the non-recurring engineering effort to be shared between many systems.

When no critical issues were detected, the waveforms acquired by the PXI system were stored and then analyzed to determine the viability of the DUT. The pass/fail disposition, the waveforms, the total energy consumed, and other test results were then passed along to a master PC that managed all these results in a database for archiving, quality control, and process improvements, each set of results being tied to the unique unit serial number.
The test systems provided reliable operation for testing the large annual production volumes of the mission-critical DUTs.

SOFTWARE FUNCTIONS
LabVIEW RT – for managing the microcontroller functions and overall data collection and safety monitoring
Microcontroller application – to provide precision pulsing of the batteries
Communicate to the host PC – to both receive pulsing instructions and configurations and to return pulse waveforms for each battery tested.
MAIN HARDWARE COMPONENTS
PXI chassis & controller
PXI DMM
PXI analog input modules
SCXI multiplexing switches
INTERFACES / PROTOCOLS:
Ethernet TCP-IP
CAN
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