Power supplies and displays for medtech and the governing standards – to ensure maximum patient and operator safety
17 September 2018
Medical power supplies differ from standard AC DC converters by virtue of having very low leakage currents. All of the medical power supplies provided by Relec Electronics meet the relevant standards, including the globally-recognised EN60601-1 and UL60601-1.
Whilst the EN60601 directive does not specifically talk about power supplies, this article looks at the relevance of the standard to a selection of medical applications, which will help engineers find the right solution.
At the heart of any product designed for the medical industry there will be a power supply that needs to meet the requirements of EN60601: a standard that has been around for over 40 years.
Safety and Isolation
Medical electronics is inherently either connected directly to a patient or operator or will be located nearby. Accordingly, EN60601 has defined the protection required to that of both the patient and the operator. A patient may be connected to a piece of diagnostic equipment by probes, whilst an operator has access to a control panel and the risks associated with faults in this area.
EN60601 2nd edition defined 3 categories of usage:
Type B (body) – This is typically equipment that may be in a clinical area, but is not directly connected to the patient. These might include beds, lighting, scanners and X-ray machines.
Type BF (body floating) – Medical equipment which is directly connected to the patient. These may include ultrasound, blood pressure monitors and thermometers.
Type CF (cardiac floating) – Equipment that is directly connected to the heart, such as defibrillators and dialysis machines.
EN60601 3rd edition took this concept further and looked at the management of risk within a product. In order to manage these risks, products have to offer multiple means of protection (MOP) and these are further broken down into 2 areas:
Means of operator protection (MOOP) – Products controlled by a technician. As a general rule MOOP has the same requirements as EN60950; however, it is essential to assess the risk of any possible contact with the patient.
Means of patient protection (MOPP) – Products directly connected to a patient.
All new medical equipment should have at least 2 appropriate MOPS. These can be either safety insulation, defined by creepage and clearance distances; protective earthing; or otherwise a combination of the 2. Where protective earthing is used, designers must be aware of the constraints on leakage currents, especially on patient-connected equipment.
Relec Electronics have a wide range of products available that meet the requirements of multiple MOPPS and MOOPS, and which also meet the latest requirements for EMC standards – which will become an integral part of EN60601 4th edition.
The portfolio includes a broad range of power supplies and DC DC converters.
External power supplies
An extensive range of plug-top and desktop designs, starting at 5W through to 300W. These products are also classified to CEC level VI, making them suitable for export to the US market. These external power supplies typically meet the requirements of 1 x MOPP.
Embedded AC DC Converters
This range includes open frame and enclosed power supplies, offering 2 x MOPP as standard. Power ranges from 40 Watts to 1800 Watts in single and multioutput configurations. The company can now also able to offer products that can be accurately controlled by means of PMBus.
DC DC Converters
1 Watt to 6 Watt converters, offering 6000V DC isolation (2xMOPP) are a simple way to power sensors and actuators, which may be connected directly to the patient.
Display technology for medical applications
RELEC has a range of standard TFT display products that are available in a wide range of sizes, from small 1.77” up to 12.1”. These cover all industry standard resolutions, sizes and interfaces. Standard units are available with brightness levels exceeding 1500 cd/m².
The company can also offer a range of enhancements to improve the optical, mechanical and environmental performance of the display, making them suitable for medical applications.
The anti-bacterial (AB) surface treatment is a coating that is applied to the cover glass. Nano-silver technology is widely used in the medical world, and when combined with a SiO2 layer, breaks down the bacterial cell wall and reduces bacteria reproduction by 99.999%. The AB coating has no effect on any optical characteristics of the display, nor does it affect the sensitivity when used with a touch panel. Popular applications of this surface treatment include heart monitors, dialysis machines and reception kiosks.
The anti-glare (AG) surface treatment is a cost-effective solution to reduce glare and any unwanted reflections. This might be especially important if equipment is used outdoors or even an operating theatre environment. In normal circumstances, light reflects in a predictable way: this is either specular or diffused. Once light strikes an AG-coated display, it is dispersed in different directions, which effectively reduces the glare. The AG coating has no effect on the optical characteristics or sensitivity when used with a touch panel.
Anti-fingerprint (AF) surface treatments reduce fingerprint marking when users directly handle the display. This is most commonly combined with a touch panel. The AF treatment is a spray coating, which is applied to the front on the module and uses fluoride nano-molecules within the coating. This isolates any natural oil on a person’s finger and greatly reduces the instances of fingerprints being transferred to the display – making the display clearer and reducing the possibility of reading errors.
Glove touch – touch panels
Relec also offers a range of integrated PCAP touch panels, which can be used with a variety of gloves – ranging from simple latex right through to Nuclear bio-medial. The high signal-to-noise ratio of our touch panels means a system can be tuned specifically to a customer’s requirement.
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