The design of a ferrofluid magnetic pipette.
An electromagnetic pipette using a ferrofluid was designed to sample liquid volumes smaller than 0.2 microliter. Submicroliter sample sizes are desirable for reducing the amount of costly reagents and reducing sample requirement for large-scale analysis. The pipette consists of four electromagnets arranged such that air-gaps are aligned to accommodate a tube. A light-hydrocarbon-based ferrofluid is contained in the tube and acts as a plunger. The position of the ferrofluid in the tube was controlled to within 0.2 mm by combining adjacent air-gap magnetic fields. The position of the ferrofluid as a function of time and magnetic pressure as a function of position was measured in one electromagnet air-gap from the device. Maximum pressure measured was 770 Pa which corresponds to a maximum velocity of 0.9 cm/s. The assembled pipette weighs approximately 25 g, and it measures 4 cm long, 1 cm wide, and 3 cm high.
Greivell
N E
NE
Center for Bioengineering, University of Washington, Seattle 98195, USA.
Hannaford
B
B
D001671:Biochemistry / Q000295:instrumentation*; D004574:Electromagnetic Fields; D055590:Electromagnetic Phenomena; D004867:Equipment Design; D011312:Pressure; D012815:Signal Processing, Computer-Assisted; D013396:Suction / Q000379:methods*; D014783:Viscosity