Case study: medical motors for anaesthesia machines

The rapid advancement of medical motor technology in recent years means that certain medical procedures like surgery under general anaesthetic and undergoing ventilation procedures are significantly safer and more comfortable now than in the past. Precisely engineered drive solutions play a vital role in enhancing the efficiency of these complex systems.

The Zeus Infinity Empowered (IE) anaesthesia machine by Dräger seamlessly encompasses a wide range of functions, spanning advanced ventilation therapy, comprehensive monitoring, integration of infusion technology and automation of sub-functions, all within a single, unified system.

Interchangeable and sterilisable turbine unit

Equipped with a turbine ventilator, this device can function as a closed anaesthesia system with complete rebreathing capabilities. Precise control over the anaesthesia gas within the closed system minimises gas consumption and anaesthetic exposure.

The turbine-based ventilation enables patients to maintain spontaneous breathing throughout the entire anaesthesia process. The turbine unit, also known as a blower unit, can be effortlessly replaced when needed and is autoclavable, ensuring sterilisation through intensive treatment with 134°C steam.

Nonetheless, stringent requirements are imposed on the system’s components as they must tolerate exposure to hot steam. All components within the turbine unit must be constructed exclusively from biocompatible materials, as they come into direct contact with the patient's breathing air. Additionally, compact dimensions and a high-power density are essential to seamlessly integrate the unit into the anaesthesia machine and facilitate easy replacement and cleaning procedures. 

Challenging requirement profile

Meeting these specifications cannot be achieved with standard ‘off-the-shelf’ components. The blower unit employs a brushless DC motor as its core drive component. FAULHABER's medical motors are engineered for demanding operational environments due to their unwavering reliability, precise functionality and extended service life. These motors are recognised for their exceptionally smooth operation, minimal noise output, high performance and agility, all within a compact form factor.

Nevertheless, developing the drive for the blower unit presented a significant challenge for Dräger’s engineers. They needed a miniature powerhouse capable of rapid acceleration and deceleration within milliseconds. 

The little powerhouse with special features

The customised brushless DC motor designed for the blower unit is encased within a robust stainless-steel housing, boasting a compact form with dimensions of just 24 mm in diameter and 46 mm in length. These features helped achieve the desired performance characteristics required for the optimisation of the magnets and sheets and the exclusive use of biocompatible lubricants and adhesives. 

The entire unit had to be autoclavable, which presented a material selection challenge. When choosing the ball bearings, developers collaborated with external specialists to identify the ideal material pairing compatible with biocompatible lubricants, particularly for operations at high speeds.

From a mechanical perspective, the system boasts an impressive setup — the impeller pump, responsible for creating the airflow, is directly attached to the motor. The electrical connections are seamlessly integrated into the external casing material. Additionally, the casting compound incorporates an EPROM, allowing access to the drive history, operating hours count, and the serial number when required. The signals from the Hall sensors within the motor are processed by the primary system controller, which then regulates the motor in response to the specific anaes-thesia and ventilation requirements.

The entire blower unit measures 120 mm in diameter and 220 mm in length, delivering outstanding performance. 

To learn more, please visit the FAULHABER website.

EMS is the exclusive supplier of FAULHABER small DC motors and drive systems for the UK and Ireland. Whether you know the type of motor your application demands, or if you’re looking for advice on a bespoke solution, our team of engineers can provide the solution. For more information on EMS micromotors for medical and laboratory applications, click here