In recent years we have seen a lot of new technologies emerging in the user interface. But when it comes to its use in the medical instrument we need to have an interface that can withstand the harsh environment under which it is operated and yet provide safe use. Even after two-three decades we still find wide use of membrane switch in the Medical instruments. Membrane switch keyboards are the user interface, whose “keys” are not separate like a mechanical switch. They are pressure pads that have only outlines and symbols printed on a flat, flexible surface. The lifespan, durability, and user experience makes it one of the good choices for the medical instrument. Below are the few points explaining why membrane switch are still considered the appropriate choice for the medical instruments.
Membrane switch does not have gaps between the keys, they are smooth and the surface is completely sealed. Thus there no chance of dust settling between the gaps. Whereas mechanical switches attract all kinds of dirt that get assembled in the cracks in the sockets where they get installed. The medical device surface has more chances of exposure to bacteria considering the environment under which it is used. Thus risking the health of the operator. To avoid such contamination, overlays have an additional coating of the anti-bacterial coating.
With no gaps between the keys, there is less chance of water or any other chemicals entering the socket and resulting in a short circuit. The membrane switch is completely sealed under the graphic overlay. Switches offer water resistance up to IP67 and also protect the user interface against scratches.
Membrane switch is a good option in cases where there is a constraint on space utilization. Low weight and flat design accommodate the switch in lesser space as compared to the bulky keys in mechanical switches. A single surface gives a membrane keypad the added advantage of being more compact than a mechanical keyboard. Thus can be used in the small portable device too.
The overlay of the membrane is made up of polyester, polycarbonate, silicone, or combinations of these materials. These materials show good resistance to heat, UV rays which means it will resist yellowing,and also some materials do provide antimicrobial protection. They can handle a high number of ‘keystrokes’. Membrane switches typically have four or more layers. The graphics are printed on the backside (beneath the membrane) so that in time the visuals don’t degrade and cleaning won’t fade away the symbols. Thus maintaining the quality of graphics for a longer duration.
Keys have a tactile touch. This gives immediate feedback on the completion of operations, enabling the medical personnel to understand the action is complete. Such quick action is a very effective way of user experience for medical personnel that is using a device while keeping eye contact with the patient. Thus reducing their operation time on the device.
Compared to mechanical switches, membrane switch is easy to customize and built as per the client requirement. User Interface can be customized to meet almost any aesthetic specification. The material used for manufacturing gives good customizable options at a low cost.
The graphical overlay on the medical device provides a 180-degree radius view. This helps in viewing the display from a far distance e.g. warning lights or other functional indicator lights can be viewed from a distance. Thus helping in good monitoring of the patients.
The keys contain a light underneath. The backlight illuminates the letters and symbols on the keys to make them visible in low light environments. This helps the medical staff read using the backlighting indicator to show certain functions are active thus highlighting important factors.
The membrane can be customized for protection from Electrostatic Discharge (ESD), Electromagnetic Interface (EMI), and Radio Frequency Interface (RFI).This can be achieved by the use of foil, transparent film, or printed screens. This shielding improves the lifespan of the devices and makes it more safe and reliable.
All membrane switches comply with Restriction of Hazardous Substances (RoHS). RoHS restricts the use of specific hazardous materials found in electrical and electronic products. Membrane switches meet these strict standards, by using polyester film and polymer ink.
In short Robust, reliable, easy-to-use, and hygienic: membrane switches make a perfect fit for medical devices.