• Optimal actuator operating forces must respect IEC requirements, recognize the size and gender of the user, account for the variety of foot wear worn by the operator (including surgical booties), and be consistent with the operator’s position (standing or sitting) during use. The implications of these diverse variables demand careful consideration of the implications of minimum actuator operating forces on user compatibility, user comfort, and fatigue.

• Optimal actuator style and location need to address function. The diversity of medical applications, and the growing number of features offered by medical device OEMs, often requires multifunction foot controls. For example, electrosurgical generators typically require two or three functions; positioning systems may need two to eight functions - plus “memory” recall actuators; and surgical microscopes often require up to eight functions. While the standard foot pedal – equipped with reed switches, micro switches, potentiometers, and Hall-effect transducers, could be used for each function, other design considerations such as foot control footprint size and ease of use, may demand other actuator styles. An effective design may require blending of pedals, rocker switches, pushbuttons, joy sticks, sliding switches, joy pads, and customized actuators designed for the needs of the specific application. Each of these must be designed and efficiently located, with careful attention to actuating force, sealing, frequency of use, protection against simultaneous operation, and labeling.

Simple design and custom graphics contribute greatly to user-friendly operation worldwide of examination chair control.

Low-profile console meets IEC “protection against inadvertent operation” requirements for laser-based dermatology device.

• Optimal stability via foot control base pads that assure stability during normal use, while allowing the unit to be repositioned during a procedure by the user without lifting it from the floor. Depending upon the application, optimal bottom pad design requires consideration of shape, geometric pattern, material of construction, the floor surface on which it will be used, the presence and type of liquids on the floor, conductivity requirements, and compatibility with cleaning solvents.

• Electrical and electronic functionality for foot control signals of less than 100mA, generally at 5V to 30 VDC. While these loads can be addressed with electromechanical switches and potentiometers, they present the designer with the opportunity to use other longer-life, higher-reliability signal sources such as magnetic reed switches, Hall-effect sensors, and foil sensors. In addition, depending upon the OEMs device design, medical foot controls may be required to interface via USB, RS232, RS 485 or some other protocol. These options, and the diversity of solutions, present the designer with the challenge of choosing the best alternatives for optimal performance.

• Patient safety and compliance addresses patient vulnerability and other assessed risks inherent in medical applications and calls for compliance with considerably more stringent industry Directives and Standards. Among these is the Medical Device Directive 93/42/EEC, IEC 60601, UL 601, CSA 22.2-601, TUV “GM” requirements, EMC Directive, Low Voltage Directive, and FCC requirements (for wireless devices). With specific IEC application requirements such as conductive foot pads for electrosurgical generator applications; protection against inadvertent operation for laser-based medical devices; and IP X8 submergibility requirements, medical-grade design requirements continue to become more demanding.

• Aesthetic compatibility strives for a foot control that complements the aesthetics of the medical device that it controls. Doing so, without compromising ease-of-use, may represent the most difficult design challenge.