Medical Device Switches Have New Communication Protocol

Author: 
Bob Michaels
Steute’s wireless transmitter-receiver module is designed to control foot and hand switches in medical device applications.
As foot and hand controls become increasingly prevalent in doctors’ offices and operating rooms for powering a range of medical devices from lasers and drills to bone saws and aspirators, medical professionals are demanding that cables give way to wireless communications. While functionally suitable for medical device applications, such technologies as BlueTooth, ZigBee, wireless LAN, and infrared-based communications can have drawbacks, including high power consumption, long wake-up times, or unidirectional communication. With the development of its 2.4-MED wireless protocol, Steute Meditech Inc. says that it has overcome these issues.

“Like other radio-frequency (RF) communication protocols, ours operates in the internationally accepted 2.4-GHz band,” remarks Peter Engstrom, Steute’s managing director. “However, we decided to develop a protocol in that band that has characteristics that make it more suitable for medical device control applications.”

Though it can be used with medical devices, an RF technology such as BlueTooth is designed for general-purpose applications. The 79 channels in its frequency-hopping scheme also result in higher power consumption than Steute’s protocol, which draws only 25 mA of power. This, in turn, affects battery life. Because BlueTooth-, ZigBee-, and wireless LAN–enabled devices typically consume larger amounts of power than the Steute protocol, their batteries must be recharged or replaced more frequently.

In contrast to BlueTooth’s 79 channels, 2.4-MED operates on 32, minimizing channel hopping without compromising noise immunity. In addition, its sleep mode reduces power consumption to 6 µA when control is not required. “If we put the device into sleep mode whenever control is not required during a procedure, we get many more hours of service from the transmitter batteries than we would if we had it communicating bidirectionally at full power all the time,” Engstrom says. Moreover, while BlueTooth-driven devices awaken in 1 to 5 seconds, devices using Steute’s technology awaken in less than 200 milliseconds, according to Engstrom.

Another feature of 2.4-MED is its bidirectionality. With bidirectional technologies, the software can be configured so that the receiver looks for certain types of signals from a transmitter, Engstrom says. In addition to encrypting the transmitter with an identity and pairing the transmitter and receiver, bidirectional technology allows the receiver to tell the transmitter that it has received the signal while allowing the transmitter to send real-time battery-charge status.

Steute is currently working with medical device OEMs to implement wireless control in applications with foot and hand switches, including radiological and surgical equipment.

Steute Meditech Inc.
Ridgefield, CT
www.steuteusa.com