It has been estimated that the average American can expect to undergo almost 10 surgical procedures, over half of which will be invasive, during their lifetime. This may seem high for a population average, but it adequately illustrates the point that you are likely to require invasive surgery at some point. And all surgery comes with risk, which is why stringent medical device testing is required for equipment that comes into actual or near contact with the patient.
In Part 1: Regulation and Standards of this series, we overviewed the extensive regulation that permeates the medical device industry and discussed ways to ensure that your contract manufacturer (CM) is able to assist you in meeting the rigid criterion for developing these critical devices. In Part 2: Development, we presented essential keys for your medical device development plan. Now, in the third installment of this series, let’s take a more in-depth look at what medical device testing is required for some of the more common equipment types used for direct patient contact and laboratory testing.
What Equipment Undergoes Medical Device Testing?
Regulation is pervasive and encompasses virtually every area of the medical devices industry. Testing, in particular, extends to equipment used in medical facilities such as hospitals, clinics and physician’s offices, research laboratories and academic institutions. The primary agency for medical device testing is the International Electrotechnical Commission (IEC), which classifies testing based on the patient’s interaction with the equipment. Following this convention, we can classify often-used medical devices that contain electronics and PCBs, as listed below.
Direct Patient Contact Equipment
- Defibrillator – used to restore the patient’s heart rhythm.
- Audiometer – used to check the patient’s hearing.
- Tympanometer – used to test the patient’s ear canal.
- Electronic blood pressure monitor – used to measure the patient’s systolic and diastolic blood vessel pressures.
- Electronic thermometer – used to measure the patient’s body temperature.
- Pulse oximeter – used to measure a patient’s blood oxygen level.
- Electrocardiography (ECG or EKG) machine – used to measure the patient’s heartbeat.
- X-ray machine – used to inspect the patient’s internal organs and tissue using x-ray radiation.
- Computed tomography (CT) scan machine – used to inspect the patient’s internal organs and tissue using multiple angled x-ray images.
- Magnetic resonance imaging (MRI) machine – used to inspect the patient’s internal organs, tissue and bones using a pulsed magnetic field.
- Colposcope – used to inspect the patient’s cervix.
- Robotic surgery equipment – used to assist surgeons in performing invasive procedures on the patient.
Laboratory Test Equipment
- Microscope – used to view and inspect small structures.
- Electrophoresis device – used for DNA separation.
- Chromatography machine – used to separate compounds into base elements.
- Hematology analyzer – used to characterize and count blood cells.
- Reflotron – used to quickly measure certain parameters of blood, plasma or serum.
- Colorimeter – used to estimate blood parameters; such as glucose, hemoglobin and creatine.
- Centrifuge – used to separate different fluids or fluids from solids.
The lists above are not exhaustive, as there are many specialized medical devices; however, these are the most commonly produced and utilized medical devices.
What Medical Device Testing is Performed?
In addition to other mechanical, thermal or chemical requirements, medical equipment that is powered by, accepts, processes or generates electrical energy must undergo specific testing requirements under IEC 60601-1 and IEC 61010-1. In the table below, common test types are presented along with their associated purposes.
MEDICAL DEVICE TESTING TYPES AND PURPOSES
|Type of Test|
Purpose of Test
|Leakage Test 1: Earth leakage current |
|Measures the level of current flowing through the earth conductor (ground) through the patient.|
|Leakage Test 2: Patient leakage current|
|Measures the level of current flowing from the power terminal through the applied part, the part in contact with the patient, during normal operation.|
|Leakage Test 3: Voltage mismatch|
|Measures the difference between the power and ground conductors to determine leakage current.|
|Energy reduction||Defibrillator test to measure the amount of energy and waveform due to defibrillator use.|
|Power supply interruption||Measures the response of the equipment to various voltage changes.|
|Rechargeable battery overcharge/discharge||Measures rechargeable battery’s response to attempted overcharge and during discharge.|
|Mains transformers||Measures the performance of a mains connected transformer in line with the equipment.|
|Potential equalization terminal||Measures the level of potential variation between conductor terminals.|
|Protective earth connection impedance||Measures the variance in resistance between earth ground conductor and the equipment metal outer case.|
|X-radiation||Measures the amount of radiation patient is exposed to during x-ray examination.|
|Defibrillation proof of applied part protection||Measures the voltage difference between the two applied parts of the defibrillator.|
Most of the tests above can be broadly classified as safety measures to protect patients from an inaccurate diagnosis or prognosis that may lead to a wrong medication being prescribed or unnecessary surgery being performed, which could result in injury or, in extreme cases, death. Others are to prevent patients from being subjected to potentially harmful electricity or electric energy. The need to adhere to these medical device testing requirements is clearly justified when we consider the potential damage that could occur from using faulty and unreliable equipment.
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When designing critical systems like medical boards, devices or systems, you should rely on a CM that has experience manufacturing PCBs for medical device suppliers. Tempo Automation not only builds boards for critical systems but is also well-versed in design and development constraints as well as quality control measures to assist you in meeting regulatory requirements.
And to help you get started on the best path, we furnish information for your DFM and enable you to easily view and download DRC files. If you’re an Altium user, you can simply add these files to your PCB design software.
If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on medical device testing or how to incorporate your design into a CAD format, contact us.
1 From a study by the American College of Surgeons, Massachusetts Chapter. http://www.mcacs.org/abstracts/2008/p15.cgi. Accessed on 10/11/2018.