What is a Medical Device?
Medical devices are instruments used to treat people for disease or injury without the use of pharmaceutical means. Medical devices are tested to prove safety (does not harm people) and efficacy (it does what the manufacturer claims it does.) Regulatory agencies require extensive documentation and test procedures to prove safety and eafficacy.
Examples of Medical Devices:
A wide range of medical devices are available on the market today. They cover all aspects of the physical condition. Here is an example set of devices:
· Audiology – hearing aids
· Cardiovascular – defibrillators, pacemakers, stents
· Tissue Engineering – artificial muscle tissues
· Dental – caps, crowns, etc
· Urologic -- catheters
· Orthopedic – artificial hip joints
· Drug Delivery --syringes
· Ophthalmology – contact lenses
· Others -- electronic thermometers, glucose monitoring devices
Trends/Growth in Medical Devices
The Life Science industry is growing at a steady rate. This growth is driven by several factors including:
· Aging of the population
· Advent of managed care and cost containment
· Miniaturization of devices and equipment
The aging population demands greater resource investment into the Life Science area. The goal of cost containment is to encourage patients to minimize time in the hospital which in your turn drives the need for devices that can support healthcare in the home. Finally, miniaturization of devices requires manufacturers to perform precision machining and testing on components and parts used to build the device which in turn drives the demand for automation. Each device area has its own growth drivers. For example, in the Cardio Rhythm Management market, growth is due to an increase in sales in Asia such as to India and China, the aging of the population in the Western world, and an increasing demand for lower end devices.
The elements of a medical device to be tested
In testing a medical device, there are five major elements to cover:
· The first is the display of the unit. The graphical display must be tested to ensure all pixels are working, and the output on the display is correct for the functioning of the device. NI offers vision tools to perform this type of testing.
· The second area is battery testing. Most devices require battery power even if only for data backup purposes. NI provides modular instrumentation including Digital Multimeters and Switching to perform battery tests. Also, switching tools are available for manufacturers who want to test multiple units at the same time or minimize the number of instruments needed for a test cell.
· The third area is power. The unit must be tested to ensure the user does not receive a shock from the power supply.
· The fourth area is Electromagnetic Emissions/Immunity testing. These tests ensure that the medical device does not radiate EMI or malfunctions from susceptibility to EMI.
· Finally, many medical devices use electronics that must be tested for functionality.
The digital thermometer is an example of a medical device requiring testing. The tests include the following:
- Displays – LCD displays must be verified for pixel on/off, brightness, and contrast.
- Battery – current/voltage draws must be tested as well as the life cycle of the battery under maximum usage conditions.
- Temperature accuracy – the accuracy of the temperature readout must be calibrated and measured.
- EMC – electromagnetic emissions must be tested to ensure the unit is not radiating EMC signals beyond the allocated spectrum.
- Internal Self Tests – must be performed to verify proper functioning.
- Computer interfaces – for those devices designed to connect to a computer, the interfacing (serial, parallel, etc) must be tested.
Other outputs – if the digital thermometer generates analog voltage, analog current, frequency, or alarm signals, these must be tested for accuracy.
In addition to testing the basic functionality of the device, other tests may be performed. These include safety, environmental testing such as shock, vibration, thermal, humidity testing, etc, biocompatibility and sterility testing, and life-cycle testing.
What is Software Validation
Validation requirements demand that manufacturers test and document software to prove the software performs as the manufacturer describes. Through a series of module and system level testing, the manufacturer proves the functioning of the software.
Documentation is generated to describe the testing process and verify the test results. Software validation mimics the clinical process which demands predictive results. The testing should prescribe the results. For example, if testing ten units produces two failures then were those failures predicted by the experimental setup or did they just happen for no apparent reason?
Software validation is achieved through a combination of process, testing, and code review techniques. A process must be in place for designing, reviewing, testing, and validating the code. Test setups must be employed to test the software on both the modular and system level using a variety of inputs. Code review techniques are critical in the verification of the software.
Software test validation can be divided into four categories:
- Performance – does the input of good data generate good data out?
- Failure modes – if the setup is wrong, does the test results reflect it?
- Repeatability – if one tests with the same input vectors, does one get the same output results time after time?
- Special Case – completely test dependent for specific requirements.
Testing of healthcare applications involves substantial expertise and very high costs.
Healthcare testing team assist with designing relevant test cases for comprehensive testing of healthcare products or software applications using manual testing and test automation tools (like HP Quality Center (QTP), Selenium and all).
Strong expertise is required in performing multi-platform testing, performance testing and load testing of healthcare applications