Research

The Whitesides Group (Harvard) has focused on forming electrets by several mechanisms (especially charge injection and ion exchange), and in using electrostatic fields to form patterns and position small objects. The Aksay Group (Princeton) has studied colloidal (adsorbed molecules and particles on surfaces) electrets, and their use in directed self-assembly, using galvanography, electrohydrodynamic (EHD) manipulation of suspensions, surfactant aggregation, and guided growth. The Prentiss Group (Harvard) has focused on electrostatic interactions between ssDNA and dsDNA, and monovalent and divalent ions; this interaction does not depend strictly on ionic concentration: divalent ions have a much larger impact. The effect may also depend on the length of the DNA. The Suo Group (Harvard) has studied theoretically the assembly of microspheres on a patterned electrode under the influence of an applied voltage. Here we examine the mechanics of this process, which rationalizes experimental observations, provides scaling relations, and suggests modifications of the process.

Research Topics include:

Directed Self-Assembly

Formation of Electrets by Ion Exchange

Formation of Patterned Electrets by Charge Imprinting Using Patterned Electrodes

Electron Transport through Organic Thin Films

Mechanics of Assembling Microspheres on a Patterned Electrode

Galvanography

Intrinsic Convective Flow on Metal Corrosion

Seeded Growth of Large-Area Colloidal Single Crystals 

Continuous and Pulsed EHD Printing

Statics and Dynamics of Surfactant Surface Aggregates

Electric Field-Guided Growth of Mesoscopic Silica Thin Films

Theoretical Modeling of Contact Charge Separation

Impact of Magnesium Ions on the Unzipping of the lambda-Phage DNA

Electrostatics in Biological Systems (NIH)