Liquid as a suspending medium serves as an ideal environment for the study and manipulation of biological molecules. These molecules, often idealized as spherical particles are typically on the order of nanometers to microns in size and can be affected in a variety of ways, including optically, electrically, acoustically, and mechanically. The Biomedical Engineering Lab is currently using the electrical methods of electrophoresis (EP) and dielectrophoresis (DEP) to assess the validity of a novel electrode material for particle manipulation.
Video: Particle alignment due to induced dipoles in an AC electric field
Left: Illustration of the differences between electrophoresis and dielectrophoresis. (a) In a uniform electric field, uncharged particles (black) are unaffected, while charged particles (black with gray shell) move towards the oppositely charged electrode. (b) In a nonuniform field, uncharged and charged particles can be directed based on positive or negative dielectrophoresis as a function of the particle and medium properties as well as the electric field.
Right: Modeling the magnitude of the electric field between triangular and rectangular electrodes.
(A) Controlled environment chamber
(B) 3D manipulator for removal capillary
(C) 3D manipulator for deposition capillary
(D) Electromagnetic solenoid plunger
(E) Syringe pump
(F) Solid state relays
(G) National Instruments DAQs
(H) Computer with LabVIEW program.
Cryogenic transmission electron microscopy (cryo-TEM) is a widely used tool for morphological analysis in biology, chemistry, and polymer science. Using this technique, samples can be imaged in their native environment without fixing or staining, which often cause fundamental conformational changes. The Biomedical Engineering Lab has developed a novel platform that boasts sub-second time resolution, native sample morphology and low sample loss through minimized adhesion due to our use of glass capillaries leveraging capillary action to prepare samples. Currently we are using our novel platform to determine the effects shear has had on samples prepared using commercial instruments that can alter sample morphology.