A wide variety of requirements – always the best solution
More than in almost any other industry, the requirements for a touchscreen or a touch system are as diverse and extensive as in medical technology. On the one hand, this is due to the wide range of applications and the very different requirements associated with it. But also with the fact that one and the same medical device can be used in completely different environments.
With regard to the materials used, finishes, technology (resistive or projected-capacitive) and the design, it makes a difference whether, for example, a diagnostic device is used in the treatment room of a hospital or in an ambulance. In the first case, electromagnetic compatibility or privacy protection, in the second case, robustness, resistance to vibration or even a special touch response time can be in the foreground.
Like hardly any other manufacturer of touch systems in medical technology, Interelectronix offers highly specific touch panels and HMIs (Human Machine Interface) for both resistive (glass-film-glass) and projected-capacitive (PCAP) touchscreens that are precisely designed for each application. And not only in standard sizes, but also in any desired special size.
Acid-resistant
An important requirement for touchscreens that are installed in medical devices is permanent acid resistance. Many cleaning agents and disinfectants contain chemical substances such as alkalis and can permanently damage the surface of a touchscreen. ULTRA GFG touchscreens from Interelectronixare particularly suitable for this requirement.
Due to the chemically resistant micro-glass surface, they are insensitive to chemicals. Even regular contact of the glass surfaces with chemicals and harsh cleaning agents over long periods of time does not cause wear or impairment of functionality.
Waterproof
A significant advantage of the micro-glass surface used by Interelectronix is that a touch system (resistive or capacitive) becomes waterproof in conjunction with the appropriate sealing system. In contrast to polyester (PET), glass is an absolutely impermeable material.
We offer seals in accordance with protection class IP69K. Seals that comply with protection class IP69K are particularly resistant to the effects of dust, foreign bodies, chemicals, steam or water (even with high-pressure cleaning).
Alternatively, a full-surface lamination of the touchscreen is also possible. Films and lamination processes are used, depending on the desired technology (resistive or capacitive) or the surface (glass or plastic). A limitation with regard to this method of achieving complete watertightness may be the simultaneous requirement for acid resistance.
Depending on the application profile of the medical device, we carry out standardised water protection tests on behalf of our customers, from dripping water testing (IPX1) to strong jets of water at 100 l/min or 10 bar (IPX6 or IPX6K) to permanent immersion (IPX7 and IPX8).
Protection against dirt
A daily problem in the medical environment is the protection of a touch screen against dirt. In hardly any other area of application is hygiene as important as in medical technology.
One way to counteract the penetration of dirt into the interior of a touchscreen as well as to clean surfaces more easily is full-surface lamination. A continuous front foil makes the surface of touchscreens insensitive to dirt and liquids.
The lamination process is therefore particularly suitable for applications with a high degree of contamination. A highly transparent lamination enables a homogeneous, flat unit of the touchscreen surface in the complete touch panel. This makes it easy to clean and disinfect the entire touchscreen without allowing liquids to penetrate inside.
However, the foils and lamination processes used depend on whether it is a resistive touch screen (glass-film-glass) or a projected capacitive (PCAP) touch screen.
In addition, the touch system should be installed without dirty edges.
Optimal readability on the touchscreen
Optimal readability of the information displayed on the touchscreen can be "life-saving" in medical technology. However, the task is anything but trivial and must take into account the future environment and the area of application with regard to the planned technical solution. Medical devices can be used, for example, under very bright light in the operating room, in darkened rooms or in rooms with changing daylight and artificial light. Other light sources from other devices in the immediate vicinity may have to be taken into account.
If you build a glass screen in front of a display, the total reflection increases by about 10%. Depending on the ambient light conditions, the readability of the display is severely disturbed by the extra reflections.
Optical bonding:In the case of capacitive touchscreens, it is possible to almost completely eliminate the reflection of the surface by means of a special bonding process, optical bonding.
Optical bonding leads to two main optical effects:
- Improvement of contrasts
- Reduction of reflection
By bonding the touchscreen protective glass to the display using a super-transparent adhesive, the two reflective surfaces (display front and glass back) are optically neutralized. The result is displays with excellent readability even in extreme lighting conditions, the best contrasts and low reflection.
Anti-reflective coating:GFG resistive touchscreens, on the other hand, can use anti-glare lenses to prevent directional reflection. AR (anti-reflective) coating lead to a reflection suppression of the reflection light level by about 90%.
When it comes to anti-reflective coating, you can choose between
- an optical lambd 1/4 anti-reflective coating (anti-reflective coating)
- and a mechanical anti-glare anti-reflective coating
choose.
It goes without saying that a combination of anti-glare lenses and an anti-reflective coating (= AR coating) leads to the best optical result. In the application, this means that a good display contrast is generated even in high interference light environments.
Sunlight readability:In the development of touchscreens in the field of medical technology, the requirement for good sunlight readability is not taken into account. However, sunlight readability is necessary for all medical devices used in patient rooms, such as handhelds or medical devices used in emergency medicine. A significant improvement in the area of solar solubility Interelectronix achieved with the use of circular polarization filters. Light is an electromagnetic wave that oscillates at right angles (transverse) to the direction of propagation. Here, light can oscillate in all possible directions or planes at right angles to the direction of propagation.
A polarizing filter only allows light to pass through that is in the polarization plane of the filter. As a result, the light that leaves the polarizing filter is always polarized. The polarizing filter acts as a polarizer for light, which is based on dichroism, i.e. it absorbs complementary polarized light instead of reflecting it like polarizing beam splitters.
EMC - Electromagnetic Compatibility
Electromagnetic fields and radiation are important in medical technology in several ways. On the one hand, the electromagnetic radiation of devices in medical applications must be particularly low in order not to influence other devices through radiation radiation.
On the other hand, a medical device must be as insensitive as possible to electromagnetic radiation in order to work flawlessly. This requirement becomes all the more important the more devices there are in a room.
With regard to the patient and the medical staff, electromagnetic radiation is also of considerable importance. Even if there are no conclusive research results on the non-thermal effects of electromagnetic fields on the human body. Nevertheless, there are indications that electromagnetic fields have a negative effect on the human organism.
For the reasons mentioned above, there is a need to develop touchscreens that have the best electromagnetic compatibility.
An optimal product in this context is the patented ULTRA touchscreen from Interelectronix, which is equipped with an ITO mesh finish. The resistive ULTRA touchscreen performs above average in EMC tests and is ideally suited for use in medical devices.
In this context, the "protective measures to reduce the risk of electric shock to the patient" according to the IEC 60601-1 standard (MOPP Means of Patient Protection) as well as protective measures regarding "patient leakage current", which are strictly observed by Interelectronix in the design of touch systems and HMIs, are also relevant.
Scratch resistant
In order to ensure a long service life of a touchscreen in medical technology, the scratch resistance of the surface of a touchscreen is an important criterion. The microglass surface used by Interelectronix , which is used for both resistive and projected capacitive touchscreens (PCAP), is so scratch-resistant that even sharp objects do not scratch the screen or affect its functionality.
This means that the touchscreen can be easily operated with a scalpel or any other object without being damaged. This allows the surgeon to quickly operate a touchscreen without having to put down the scalpel.
Usability with gloves
An important requirement criterion in medical technology is the operability of medical devices with gloves. Which is the right technology depends a lot on the area of application and the type and material thickness of the glove.
Due to their technology, resistive touchscreens such as the patented ULTRA GFG Touch are ideal for operation with gloves of all kinds. The resistive GFG touchscreen already reacts "to light pressure" and can therefore be operated with any glove.
A projected capacitive touchscreen, on the other hand, reacts to a voltage change on its top. Contact with a conductive object triggers charge transport, which changes the electrostatic field between the electrodes and the capacitance.
Medical gloves or latex gloves are best suited for operating a projected capacitive touchscreen. As a rule, they are extremely thin, have no insulation and are used without seams at the fingertips. As a result, the required voltage change can be triggered when touched. For optimal usability, however, the controller must be adapted to the respective application and the associated response time.
Shock and vibration resistance
Shock and vibration resistance in touchscreens used in the medical environment are relevant, for example, in defibrillators for emergency medicine or in devices for patient monitoring.
The development of touch systems that have a special shock and vibration resistance requires a specific adaptation of the materials, the sealing and damping systems, the installation and the use of further finishes.
If required, Interelectronix also offers certification of the touchscreens according to individual test procedures or common standards such as DIN EN 60068-2-64 /-6 /-29.