Wireless expertise in medical technology I Wireless technology for medical devices

In the OR, medical practices and rehabilitation clinics, the staff often literally have their hands full. For this reason, medical equipment is usually operated by foot control. This complex field of human-machine interaction is the focus of steute business unit Meditec.

Good reasons for using remote control in the OR and medical practices

Nearly all of the latest steute Meditec projects exploit the advantages of wireless technology – in areas such as ophthalmology, neurosurgery, surgical microscopes and imaging techniques like CT and MRI. Examination couches and dental chairs are also increasingly controlled without cables. There are good reasons for this. Foot controls which are not connected by cable can be positioned more flexibly, facilitating more ergonomic operation of the medical device, and they are also more hygienic. The increased quality of a system incorporating a wireless user interface should not be underestimated. Remote control is a state-of-the-art technology which can help medical device manufacturers to set themselves apart from the competition.

More than thirty years of skilled development

In 2000, steute Meditec developed its first wireless foot control to run on the 868 MHz frequency band. It was for a magnetic resonance imaging (MRI) device which would be used in a shielded MRI room, making this technology a reliable and unproblematic choice. Other medical applications, however, demanded a frequency band that was freely available for other environments all over the world. That same year, a decision was made to implement the Bluetooth standard. By 2003, steute had developed its own wireless protocol suitable for medical devices. Today, steute controls using this technology can be found all over the world, with reliable signal transmission guaranteed by bidirectional communication and frequency hopping.

A wireless technology specifically for medical applications

Some extra development was still needed for the wireless systems, however, for example with regard to power consumption. This is why, in 2008, steute Meditec presented a new wireless technology developed from the outset specifically for medical applications, featuring very low power consumption, yet with reliable transmission and excellent coexistence. This technology was developed further in 2017, resulting in the version which is currently available. This SW2.4LE-MED wireless technology from steute features maximum energy efficiency in conjunction with increased transmission performance. It is used in both the standard steute Meditec products and its customised controls.

Typical application fields

High-frequency surgery

Maximum freedom and flexibility for surgeons in the OR with our wireless foot switches, ergonomically designed for the special requirements of high-frequency surgery. SW2.4LE-MED is our energy-saving wireless system – at a price which is attractive even in a market segment under extreme cost pressure.

X-ray / MRI / CT / mammography

Three-dimensional images of organs, tissue structures and bones have to be generated within seconds. Our innovative foot switches and hand controls are ideally suited to such applications. Many of our customers opt for a customised solution; alternatively they can select an already existing steute product from our wide CLASSIC LINE range.

Ophthalmology

Highly precise and intuitively operable foot switches ensure maximum fitness for purpose during phacoemulsification in the OR. Horizontal and vertical pedal actuation, programmable braking points for a precise tactile feedback, or integration of a laser control: we realise your wishes and requirements with regard to ergonomic comfort and user precision.

Microscopy

In ophthalmology and neurosurgery, surgical microscopes are used. Our bespoke foot switches for surgical microscopes, which facilitate the highest degrees of precision and sensitivity, have been defining marketplace standards for years. All actuators are arranged ergonomically and are intuitively operable for users.

Laser devices

Our user interfaces for laser medicine are protected from unintended actuation by innovative guards. And yet we make no compromises regarding fitness for purpose, and all other normative requirements are comprehensively fulfilled.

Operating tables / operating chairs

When surgical staff have their hands full, they can still move the patient on the operating table into the desired position by means of a foot control. Our innovative foot switches comply with the general requirements of the IEC 60601-1 standard. As a further option, we also offer integrated solutions.

Dental medicine

Multifunctional foot switches for speed control and chair adjustment are special features required in dental medicine. Our multifunctional user interfaces are available in different variants to meet your particular wishes. As a further option, your foot control can also be equipped with our own affordable SW2.4LE-MED wireless technology.

Moving towards the interoperable OR

In collaboration with research institutes and manufacturers of medical devices, steute Meditec is currently working on research projects which also feature wireless communication. One goal here is the interoperable OR, in which several medical devices can be controlled using a single user interface.

the integrated operating theatre

Safe wireless technology SW2.4LE-MED

State-of-the-art wireless standard for medical equipment

Signals are transmitted to the medical device via the third and latest generation of steute wireless technology. This technology features considerably reduced power consumption in conjunction with higher (and configurable) transmission performance. Although power consumption is low, the response time is very fast: signal transmission from an already activated foot control takes just 20 milliseconds.

The low-energy wireless technology used by the new steute user interfaces means that, for the first time ever, conventional alkaline batteries (e.g. AA or C) can be used instead of a lithium ion rechargeable battery. Batteries therefore no longer need recharging, eliminating both the charging devices and the charging management, which in turn reduces the costs.
The latest steute Meditec wireless technology works on the 2.4 GHz frequency band and can be used throughout the world universally and free of charge.

Low energy – short connection time

One of the features of the new, third-generation SW2.4LE-MED wireless technology developed by steute is an extremely low energy consumption during active operation of just 11 mA. Thanks to a “sleep” mode, into which the wireless foot control falls when not used for a preconfigurable amount of time, the power consumption can be reduced to almost nothing. The shift back from the low-energy resting mode to the active mode is so fast that it goes unnoticed by the user: in practice the average wake-up time in real conditions is 50 to 60 milliseconds. The entire process chain takes place within this very short period: actuation of the foot control, “waking up” of the switch, transmission of the signal, arrival at the receiver unit, processing of the signal, and switching of the output signal.

Higher and more flexible transmission performance
While the power consumption of the wireless signal has been reduced, the transmission performance is actually higher than that of the previous wireless technology generation. In addition, transmission is now flexibly configurable, meaning that, for example, a user interface controlling an X-ray device can send signals to that device from a neighbouring control room. Clear assignation of foot control to corresponding receiver via the »pairing« procedure reliably prevents erroneous signalling and also facilitates interference-free operation of several wireless user interfaces inside one room or OR.

International standards implemented
An extremely low residual error probability permits documentation of the transmission safety as below 1 x 10^-9 1/h. The wireless system hereby meets the requirements of SIL 3 (Safety Integrity Level to IEC 61508). A further advantage is its improved 128 bit-AES encryption, which also satisfies the security requirements of the FDA.

Powered by commercially available, not rechargeable batteries

The low energy consumption means that power can now be supplied by commercially available and no longer by rechargeable batteries. This means: both the effort of recharging and the charging device itself can be eliminated. With a conventional medical application profile, the batteries last for more than one and a half years, meaning that device manufacturers can replace them as part of their annual service. The battery status is displayed at all times. Should end users wish to change the batteries themselves, this is possible in a few easy steps and with no need for tools. The waterproof battery compartment simply has to be opened with a quarter-turn of the knob. The protection class of the foot control (up to IP X8) remains unaffected.

Non-tiring and intuitive operation
In addition to optimising its power supply and achieving a high level of transmission reliability and a long lifetime, the steute engineers attached great importance to the ergonomic design of this new foot control series, i.e. non-tiring and intuitive operation. Optional push buttons can be located above the pedals and are also actuated by foot. A folding bar enables the wireless foot controls to be positioned easily, while their wireless actuation gives users additional freedom of movement without the restrictions of a (potentially unhygienic) cable.

Compliant use of state-of-the-art user interfaces for medical devices

Documentation requirements for radio systems in the OR

New directives and standards, including the EU RED directive and the modified EMC directive, are increasing the levels of testing and documentation required during the development of medical devices, especially in connection with wireless technologies. This also impacts country-specific regulations regarding the use of radio equipment.

Coexistence with other radio networks

The stricter requirements for medical equipment are due to the increasing variety of wireless systems and the very high standard of safety essential to this field. Consequently, the directives play a major role in guaranteeing the coexistence of different radio systems, such as Wi-Fi, Bluetooth, Zigbee and microwaves. These inspections must comply with the relevant standards (IEEE/ ANSI C63.27), and the results must be documented.

Approvals for all major markets
Our “Classic” range of user interfaces makes it easy for customers to produce the required evidence of conformity. These standard wireless controls have all been tested in accordance with the relevant directives, and the radio module is approved for major markets such as the USA (FCC), Canada (IC) and Japan (ARIB). The medical device documentation (including test reports) is supplied with our products and can be integrated in the documentation of the end device.

Testing and documentation for customised controls
The steute development team is experienced in the individual testing and documentation of “Custom” user interfaces. The goal is to eliminate as much of the testing and documentation work for our customers as possible. The wireless controls can additionally be provided with certificates of conformity with FCC (USA), IC (Canada), and MIC (Japan), as well as with test results proving compliance with the relevant directives.

“Simplification of Approval” for wireless controls

As the marketer of the medical device, the manufacturer is responsible for proving compliance. With the tests already conducted, the documentation and the test reports, the manufacturer ultimately has to ensure that the user interface has been integrated correctly within the overall system. This requires a "delta analysis" or "gap analysis", which is simpler, faster and cheaper. This procedure is known as "simplified approval" for wireless products in accordance with the ETSI directive (ETSI EG 203 367).

"All-inclusive": certificate for global approval
On request, steute can provide a "Certificate of compliance", issued by the CSA following an independent inspection. A "CB certificate" can also be provided, corresponding to the "CB scheme" for electromedicine and accepted by international approval bodies.

Support with software testing
Individual software solutions are created for our customised user interfaces, requiring comprehensive testing and documentation. Here, the phases of the life cycle process to EN 62304 provide orientation. A test specification is drawn up prior to the programming, listing the target outcome. After programming, the target outcome is then compared with the actual outcome. The software can only be released when all tests have been successfully completed. steute Meditec can perform all the necessary tests, shortening development times.

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