Faster Blood Tests Thanks to 3D Printed Gears

Life-saving technology — a motorized system for predicting heart attacks

Cardiovascular disease is the leading cause of death worldwide, making rapid diagnosis critical when a heart attack is suspected. While laboratory blood tests can measure troponin levels within a few hours, a device developed by Cor.Sync delivers results with the same accuracy in approximately eight minutes. This speed is made possible in part by the precision of a stepper motor system which requires an angular offset of less than 0.1 degrees — a level of accuracy achieved primarily through the low inertia of 3D‑printed gears from igus®.

Profile

What was needed: Custom lightweight gears to increase the resolving power of a stepper motor system
Manufacturing process: Selective laser sintering (SLS)
Requirements: lightweight, wear-resistant, low-maintenance, lubrication-free motion plastic solutions.
Material: iglide® i3
Industry: Medical technology
Success through collaboration: Overcoming the technical obstacles to develop the patented technology for increased predictability of heart attacks

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Problem

To allow the troponin concentration in the blood to be recorded accurately, a 0.9 degree stepper motor was coupled in series with two gears — both of which have a transmission ratio of 100:1. What still stood in the way of the resulting resolution of 0.00009 degrees was the increased inertia of the system due to the metal gears. A lighter material was needed so that the torque of the stepper motor could overcome the inertia of the system.

In addition, a hospital environment requires special operating conditions. Being unable to use the device while performing maintenance could cost some patients their lives. This maintenance time can be reduced if the gears could run lubrication-free. Furthermore, lubricants could pose a biological hazard during blood tests.

As far as the gears are concerned, Cor.Sync initially tested several metal models. Once a suitable device had been found, a lubrication-free implementation option was sought.

Solution

In hospital environments, the use of lubricants is avoided, as these can worsen the spread of infectious agents. For this reason, iglide® i3 gears were used.

The 3D printing of the gear from the wear-resistant iglide® i3 plastic fulfilled every requirement. Thanks to the 3D printing service from igus®, the desired design could be realized with minimal inertia. In addition, the system's freedom from maintenance was guaranteed thanks to the self-lubricating polymer gear.

Other self-lubricating igus® components in other parts of the device as well.The optical system, for example, consists of laser diodes, photodiodes and other components which have to be aligned with each other. For this purpose, the optical elements were mounted on drylin® W cam slides, which slide over a drylin® W double rail ensuring the concentricity and alignment of the optical system.

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