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.
The SW2.4LE-MED wireless technology in detail
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.
Power consumption in comparison
Documentation requirements for radio systems in the OR
New directives, standards and other requirements mean that the amount of documentation generated during the development of a medical device has increased considerably. Manufacturers should be aware that this is also true for wireless technologies. The EU “Radio Equipment Directive” (RED), which replaced the previous R&TTE directive has led, for example, to more compulsory inspections and more documentation. This is the case for the modified EMC directive for medical devices (IEC 60601-1-2:2016) as well which came into force in April 2017, and can also be the case for country-specific regulations regarding the use of radio equipment.
Coexistence with other radio networks
The stricter requirements are partly due to the fact that different wireless systems are increasingly at work in neighbouring medical devices – also and especially in the OR – and that a very high standard of safety must still be guaranteed.
Consequently, coexistence – potential mutual influencing of different radio systems – plays a major role in the various directives. For example, a coexistence inspection is mandatory for many radio networks and frequencies (Wi-Fi, Bluetooth, Zigbee, microwaves…). Conduction of these inspections must comply with the relevant standards (to IEEE/ ANSI C63.27), and the results must be correctly documented. The FDA also demands that medical device manufacturers produce evidence of coexistence for their wireless systems.
Approvals for all major markets
For our “Classic” range of user interfaces, presented here, the required evidence of conformity is easy for our customers to produce. These standard wireless controls have all been tested during their development in accordance with the relevant directives as a matter of course.
The wireless module we use is approved for major markets such as the USA (FCC), Canada (IC) and Japan (ARIB). The corresponding documentation for medical devices (including test reports) is supplied with our products, making it easy to integrate into the documentation of the finished medical device.
Inspection and documentation for customised controls
For our “Custom” range of user interfaces, the abovementioned inspections must be conducted and documented individually. The steute development team is experienced in this field and has set up a routine to provide our customers with as much assistance as possible regarding mandatory inspections and documentation.
The documentation always supplied with wireless controls from steute Meditec includes certificates of conformity with e.g. FCC (USA), IC (Canada), and MIC (Japan). The test results refer to the relevant directives (RED, EMC…) and the standards which are necessary to satisfy them, thus documenting that the wireless system complies with these directives.
“Simplification of Approval” for wireless controls
Ultimately it is the manufacturer, as the marketer of the finished medical device, who is responsible for producing this evidence. However, with the tests which steute has already conducted and the corresponding documentation including the test reports, the manufacturer only has to check the results of these tests to make sure that they are still appropriate once the user interface has been integrated within the overall system.
This procedure is known as “delta analysis” or “gap analysis”. It is far simpler to perform and thus faster and also cheaper. For wireless products which must comply with the relevant standards, the procedure is known as "Simplification of Approval" in the sense of the ETSI directive (ETSI EG 203 367).
“All inclusive”: certificate for global approval
After inspections and documented testing of its wireless (and customised) user interfaces, steute can optionally provide a "Certificate of Compliance", issued following an independent inspection by the CSA. Moreover, steute can manage the issuing of a "CB certificate" in line with the "CB scheme" familiar from electromedicine and accepted by international approval bodies.
Support with software inspections
Since individual software is created for our customised user interfaces, here too extensive inspection and documentation obligations apply. The various phases of the life cycle process to EN 62304 must be observed, and during the inspections all functions in the software specifications are checked. For this purpose, test specifications are drawn up prior to the creation of the software code, listing the target results. After programming, the target results are then compared with the actual results. The software can only be released when all inspections have been successfully completed. Here too, steute Meditec can assist customers by managing these inspections and thus contributing to shorter overall development times.
Full Modular Approval:
- USA: FCC
- Canada: IC
- Europe: RED
- Japan: ARIB
IEC 60601-1 by CSA