Digital Designs and Scientific Hardware - Open-Source Lab: How to Build Your Own Hardware and Reduce Research Costs - page 233

up to 4000 RPM on 4.5 V/100 mA USB port power giving a centrifugal force of 500 g . The USB
centrifuge can be placed in either a printable enclosure or any other appropriate enclosure to
make a functional very inexpensive low-end centrifuge.
FIGURE 6.74 USB powered cytocentrifuge.
To fabricate the USB centrifuge, print out the parts, purchase an appropriate DC motor, the
speed controller and assemble. Similar to the Dremelfuge, the printed parts that experience
physical forces should be printed at 100% fill. In the example shown, the US$8 DC motor speed
control PWM is part number FK804 from Bakatronics. The potentiometer controls the width of
the pulses to control the speed of the motor. It can be mounted directly on the unit, remotely
on a control panel or in a printed enclosure, or in FB enclosure to make a hand-held throtle.
The USB centrifuge uses a 12C power supply, but can be used as low as five VDC. The hous-
ing is FB03 and the PCB is 1.8″ × 1.3″. The maximum current is 1.5 A. In addition, you can add
a DPDT slide switch for reversing the direction of the motor. If you do not have a small DC
motor that has speed up to 4000-5000 at 1.5-6 V, you can salvage, you can buy one for about
$3 from numerous Internet vendors. Lastly you will need an old USB cable.
Dr Richard Siderits is an excellent example of the open-source scientist of the future. He is
an Anatomic and Clinical Pathologist, fellowship trained in Experimental Pathology and he is
currently an Associate Professor at Robert Wood Johnson University Medical School, Depart-
ment of Pathology and Laboratory Science. In addition to his research, he especially enjoys
teaching rapid prototyping and science, technology, engineering and mathematics (STEM)
principles (including, of course, 3-D Printing) as they apply to the medical sciences and the
history of medicine. The shear volume of his contributions to open-source science is already
substantial. For a full list, see his Thingiverse user page. 77 In addition to the cytocentrifuge,
he has shared designs for many useful tools such as 3-D printable rapid fluid filters78 78 as seen
in Figure 6.75 , PCR tube racks 79 ( Figure 6.76 ), cassete racks 80 (used to organize cassetes that
hold tissue samples and large specimens in surgical pathology and shown in Figure 6.77 ) , and
platypus forceps 81 ( Figure 6.78 ), which hold a portion of tissue so that a scalpel or microtome
blade can slide in between and section the tissue at a uniform thickness.