Membrane switches – indispensable and highly functional components that are often the preferred choice of designers and engineers creating innovative solutions for the healthcare sector. From operating rooms to intensive care units, membrane switches are used in a wide range of equipment, providing precise control and reliability in critical situations. Qwerty specializes in developing customized solutions for clients and users in the medical industry. Here’s everything you need to know about our membrane buttons.

What are membrane switches and how do they work?

Membrane switches are technologically advanced yet elegantly simple input devices that completely change the way humans interact with machines. They consist of multiple layers, including a foil with printed circuits and a user interface element with function descriptions, a display window or service openings. We are then dealing with a membrane keyboard.

Other solutions from the HMI (Human Machine Interface) field are also possible. The glass panels combined with bonded touch panel are very popular (more on this in a separate article).

Keyboards are in fact multi-layered electromechanical devices that convert physical pressure into an electrical signal. In their design, each layer plays an important role and impacts the effective operation of the whole:

1. Top (graphic) layer – usually made of durable, transparent material like polyester or polycarbonate. It bears, among other things, button graphics, logotypes, descriptions of functions, and shorting points.
2. Separation layer (interlayer) – a thin layer with openings in the button areas, maintaining the gap between the conductive layers.
3. Conductive layer – a stiffer layer with printed conductive paths.
4. The backing layer – usually adhesive, allows easy installation of the keyboard on the device.

The working principle of the membrane switch is based on a simple but ingenious concept. When the user presses a specific point on the surface of the switch, the upper conductive layer (the shorting point) flexes, covering the distance created by the separation layer. Upon contact with the lower conductive layer, the electrical circuit becomes closed. This circuit closure generates a signal that is interpreted by the processing unit as a specific command or data input. When the pressure is released, the elastic top layer returns to its original position, disconnecting the circuit.

What are membrane switches made of?

Membrane switches are advanced designs whose effectiveness and durability depend on carefully selected materials. Each layer of the switch requires specific raw materials to ensure optimal performance and resistance to a variety of operating conditions. The usual components and raw materials used are:

• Foils – one of the basic elements are high-quality foils, usually made of polyester (PET) or polycarbonate (PC). These materials are distinguished by their exceptional durability and flexibility, ensuring long-lasting use of the switch. In addition, their transparency makes it possible to create visually appealing interfaces with backlighting.
• Conductive materials – at the heart of the switch are conductive paths, usually made of silver and graphite. They are applied using the screen-printing method, which makes it possible to create extremely precise and thin circuits. Newer technologies also use conductive polymers that offer greater flexibility and the ability to create transparent pathways.
• Adhesive membranes – specialized adhesives, often acrylic, resistant to high temperatures, are used to join the individual layers. Their proper selection helps ensure the durability and reliability of the switch, especially in harsh environments. Modern adhesives additionally offer conductive properties, which can simplify the design of the switch.
• Insulating materials – special foils or foam materials are used in the separation layer. Their job is not only to insulate electrically, but also to provide the right feel when the button is pressed
• Protective coatings – to increase resistance to abrasion or chemicals, additional coatings such as UV varnishes are used. The most recent solutions also include hydrophobic coatings for improved moisture resistance, or even coatings with silver nanoparticles for antibacterial properties.

The selection of materials for membrane switches is a complex process, taking into account not only the operating environment and required durability, but also economic and environmental aspects. Modern design trends emphasize the use of environmentally friendly and recyclable materials, which poses new challenges for membrane switch manufacturers.

Membrane switches in the medical industry

In the medical industry, membrane switches are widely used. They can be most often seen on such equipment and devices as: 

• Patient monitors – control panels equipped with membrane switches allow medical personnel to operate the devices quickly and intuitively.
• Respirators – precise control over respirator functions with membrane switches can determine whether a patient lives or dies. Their responsiveness and reliability ensure that every button press is correctly interpreted by the device.
• Defibrillators – in critical situations, when every second counts, the precision of membrane switches in defibrillators cannot be overestimated. Their resistance to moisture and shock further enhances their usefulness in emergencies.
• Infusion pumps – proper drug dosing requires a reliable operator interface. Membrane switches in infusion pumps provide precise control over the amount and rate of delivery of medications.
• Diagnostic equipment – in medical imaging equipment such as ultrasound and CT scanners, membrane switches enable intuitive operation of complex functions while minimizing the risk of accidental errors.
• Hospital beds – modern electrically operated hospital beds are often equipped with membrane switch panels, allowing patients and staff to easily adjust position.

Membrane switches in medical equipment contribute to increased patient safety and medical staff efficiency. Their reliability has made them a proven performer in critical situations, and their intuitive interfaces are easy to use under increased stress. Moreover, membrane switches are easy to clean, which is especially important in maintaining sterile conditions in the rooms of hospitals, clinics or doctors’ offices.

What other Qwerty technologies support membrane switches in medical devices?

Membrane switch technology is constantly evolving. The latest solutions use advanced conductive materials to create transparent or even flexible interfaces. 

Innovations in this field not only increase the functionality and reliability of the equipment, but also contribute to improving patient safety and the efficiency of medical personnel. Here are the key technologies that support and improve functioning of membrane switches in medical equipment.

Optical bonding

Optical bonding is an advanced technology that is revolutionizing the display quality and durability of user interfaces in medical devices. 

The bonding process involves fusing the display to the touch panel or glass front, which eliminates the formation of air pockets between the layers. This makes the image clearer and the whole structure more resistant to external factors.

In practice, this translates into sharper, high-contrast image and better visibility in various lighting conditions. The viewing angle of the display is also improved. In addition, the surface integrated in this way is easier to clean and disinfect, which helps maintain high standards of hygiene.

EMI/RFI shielding

In medical environments where many devices are operating simultaneously, electromagnetic interference (EMI) and radio frequency interference (RFI) can be a real problem. To provide protection against them, Qwerty’s membrane switches are further equipped with innovative shielding materials, such as specialized conductive foils, precision micro-grids and conductive adhesives. They form an effective barrier to protect sensitive electronic components from harmful external interference.

Such technology ensures that medical devices can function without interference even in environments with high intensity electromagnetic fields. This is essential to ensure patient safety and diagnostic accuracy.

Protection against electrostatic discharge (ESD)

Sensitive electronic devices must also be protected from electrostatic discharge, which can damage delicate components. To this end, membrane switches used in medical equipment use specialized ESD foils that act as an effective protective barrier.

These advanced materials are capable of dissipating (like a lightning rod) accumulated static electricity, thus preventing potentially dangerous discharges. This protects delicate electronic components from damage that could lead to malfunctions or complete failure of the device.

What are the advantages of membrane switches?

What makes membrane switches unique is their versatility and adaptability. They can take a variety of forms – from simple, single buttons, through elaborate numeric keypads, to advanced touch panels with LED backlighting. Their slim design allows them to be integrated into a wide variety of devices, from medical equipment to industrial equipment, while offering resistance to dust, moisture and many harsh chemicals.

Other notable advantages of membrane switches include:

• Flat design and ergonomics – membrane switches feature an extremely thin design, reaching a thickness as little as 0.6 mm. This feature not only enhances their ergonomics, but also enables seamless integration with a variety of medical devices. Their flat surface significantly facilitates the cleaning and disinfection process, which is very important in medical environments where maintaining the highest standards of hygiene is a priority.
• Resistant to external conditions – thanks to the use of sealing (e.g., IP65-compliant), membrane switches are protected from water and dust, making them ideal for use in demanding clinical environments.
• Resistance to shock and mechanical wear – membrane switches show impressive resistance to shock and impact. This is made possible by the use of high-quality materials, such as PET foil, which combines lightness with exceptional durability. The use of innovative technologies, such as optical bonding, further strengthens their resistance to mechanical damage, ensuring long-lasting functionality even in heavily used medical devices.
• Precision of operation – one of the most significant advantages of membrane switches is their extreme precision of operation. The activation force, which typically ranges from 200g to 5kg, was chosen to ensure comfort while minimizing the risk of accidental activation. What’s more, an impressive response time of no more than 0.01 seconds guarantees the system’s instant response to user actions.

This combination of features makes membrane switches indispensable in medical devices requiring the highest accuracy and trouble-free operation.

Why choose membrane switches from Qwerty?

These ultra-thin, flexible structures are the foundation of many modern user interfaces, combining functionality, aesthetics and reliability. Their versatility and durability, as well as their relatively low production costs, make them still a common choice in many devices, despite the growing popularity of touch screens.

Qwerty’s membrane switches are manufactured to specific customer requirements, allowing them to be customized to meet the specific requirements of medical devices. Among other things, we offer the possibility of modifying the activation force, as well as the types of materials and the protective layers used, which allows full customization of the product.

Thanks to shielding technology, optical bonding and the use of highly resistant materials, including special protective coatings, conductive foils and adhesives tailored to specific medical needs, our switches meet the highest standards of quality and safety. At the same time, they are characterized not only by durability, but also by high resistance to disinfectants, moisture and other harmful agents.