The figure depicts a mechanism that is capable of simultaneously rotating as many as six disposable bioreactor chambers about horizontal axes. The particular bioreactor chambers for which this mechanism is designed are high-aspect-ratio vessels (HARVs), which are round cylindrical vessels developed by NASA.

This Drive Mechanism rotates as many as six bioreactor chambers simultaneously. A chamber can be removed during operation, without disturbing the rotation of the other chambers.
The source of motion is a 24-Vdc geared electric motor with an output shaft speed of 300 rpm in the absence of a load. By means of a toothed drive belt and pulleys, rotation is coupled from the geared- motor output shaft to a drive shaft, which is located centrally relative to the axes of rotation of the bioreactor chambers. The sizes of the pulleys and gear belt can be changed to obtain different speeds of rotation.

Each bioreactor chamber is mounted on an adaptor equipped with bearings that allow free rotation about a horizontal axis. The bearings, in turn, are clamped onto a stationary retainer. A foam collar on each end of the drive shaft makes contact with the outside diameters of the bioreactor chambers, acting as a frictional coupling to transfer rotation of the drive shaft to the bioreactor chambers. The compressibility of the collar accommodates variations in the diameters of the chambers. By loosening the bearing clamp of any given reactor chamber, one can remove that chamber without stopping the rotation of the other chambers.

This work was done by Eric D. Johnston and Mitchell Litt of the University of Pennsylvania for Johnson Space Center. MSC-22860


Motion Control Tech Briefs Magazine

This article first appeared in the February, 2002 issue of Motion Control Tech Briefs Magazine.

Read more articles from the archives here.