Small drives, big benefits

Today, microdrives perform remarkably well in a wide variety of applications. Compact, high-torque, dynamic with precise control and as quiet as possible are not only requirements in many industrial applications. The same properties are also in demand in medical and laboratory technology.

In order to contain the spread of the SARS-CoV-2 coronavirus, numerous measures are being taken worldwide, some of them very drastic. At the same time, laboratory and analytical capacities need to be expanded in order to speed up tests and research into antidotes or vaccines. But the protection of medical staff who look after patients in hospitals must also be seamless and function just as reliably as the ventilators for sick people. For these vital systems, Faulhaber develops and manufactures drive systems which, in addition to meeting the high standards of EN ISO 9001 and 14001, are also certified in accordance with EN ISO 13485, especially for use in medical products. Applications range from ventilators to recording body temperature with infrared thermometry.

Ventilators: quiet operation and high dynamics

Worldwide, the demand for ventilators has increased dramatically. The drives used here have to meet high requirements. Thus, good speed controllability, low-vibration and quiet running as well as reliable and low-maintenance operation play an important role for ventilator manufacturers when it comes to airflow control. Brushless DC servo motors and DC micromotors with graphite commutation meet these requirements particularly well. At the same time, they offer great dynamics due to their low moments of inertia and high speeds can be realised.

The graphite commutated DC motors are available with diameters from 13 to 38 mm and are complemented by a comprehensive selection of standard components such as high-resolution encoders, precision gearheads and controllers. DC servo motors are available in several series. The BXT flat motors, for example, are unusually short in the axial direction. Thanks to innovative winding technology and optimised design, the motors themselves are only 14, 16 and 21 mm long, but deliver torques of up to 134 mNm with diameters of 22, 32 or 42 mm. For precise speed control or for high demands on positioning accuracy, diameter-conforming magnetic encoders or speed controllers are fully integrated into the housed motor variants, whereby the drive is extended by only 6.2 mm. The matching metal planetary gearheads of the GPT series are also characterised by short design, high torque and the finest gradations of the numerous reduction ratios.

Personal protection: High power density with compact design

Since corona viruses spread via droplet infection, respiratory protection plays an important role in personal protective equipment. Powered air-purifying respirator (PAPR) systems protect medical staff very effectively. Such portable respiratory systems, which filter air through a blower, are much more comfortable for the user than those that rely on the user's lung power.

PAPRs enable fatigue-free breathing by providing a constant supply of air. Drives that are suitable for this purpose must be powerful, but also particularly light and compact for mobile use and should work as efficiently as possible in battery mode. The already mentioned BXT flat motors are therefore also a good choice here. DC micromotors with precious metal commutation are also suitable for this area of application. They offer high power density in a compact design and have proven their durability in numerous applications. They are available in diameters from 6 to 26 mm, operate without cogging, consume very little power and are extremely light.

Laboratory automation: dynamics and precision

An important element in the fight against Covid-19 is the expansion of test capacities. The more tests that are carried out, the more can be learned about the virus. It is also important for people with symptoms to know promptly whether they have the disease. The most reliable test for detecting a Corona infection is the PCR test (polymerase chain reaction). Since this is very time-consuming, there is no way around automated laboratories with high throughput. Small servo drives for longitudinal and rotary positioning are particularly often required in the analysis devices. For these, high dynamics and precision are particularly important.

Faulhaber DC micromotors and bell-type armature motors with integrated encoders meet these requirements for continuous use in medical test laboratories. The small drives have also proven their worth in transporting samples between the individual analysis devices. Brushless DC motors, so-called flat-rotor motors, are the driving force of the transport balls that move samples back and forth between the individual analysis devices. They are designed for high reliability and long service life, so they can easily cover many kilometres in the automatic distribution systems without having to worry about wear. In addition, their quiet, cogging-free running characteristics are convincing, which is particularly important when open blood samples have to be transported.

Point-of-care analysis: compact and reliable

If test results are to be available promptly so that, for example, quick decisions can be made on the basis of laboratory values in intensive care units, outpatient clinics or doctors' practices, so-called point-of-care analyses are required (Fig. 5). They are used to record parameters such as cardiac enzymes and blood values on site or to detect pathogens such as SARS-CoV-2 in smears using PCR.

The corresponding analysers are almost completely automated, and the use of test strips means that only a few interventions by the user are necessary. Drives for this application must be as compact as possible, but also reliable and fast. Therefore, DC micromotors with graphite or precious metal commutation are a good choice here as well, but stepper motors are also a possibility. With spindles, customised pinions on the drive shaft and UL-compatible cables with connectors, they can be perfectly matched to the application.

Infrared thermometry: cost-efficient and fast

As a non-contact and mobile method for recording body temperature, e.g. at border crossings or in airports, infrared thermometry is widely used worldwide. In simplified terms, a lens in an infrared thermometer focuses the thermal energy of an object, in this case a person, onto a detector. The associated thermal radiation is converted into electrical signals and finally into an image or a numerical value. In this way, the user can quickly see whether a person's body temperature is elevated.

Stepper motors have proven themselves in these mobile measuring devices to support the infrared cameras in panning and tilting, zoom, focus or for shutter control during calibration. Without encoders, they position very precisely, making cost-effective positioning drives feasible. At the same time, they enable extremely fast changes of direction when focusing. The small drives from Schönaich thus prove once again that they advance technology in medicine, research and laboratories for the benefit of people.

By Andreas Seegen, Head of Marketing at Faulhaber, and Ellen-Christine Reiff, Editorial Office Stutensee