research:

Physics and Chemistry of Interfaces

Our work on the physics and chemistry of interfaces is directed to address the issue of chemical selectivity and sensitivity in chemical and biological sensors.

Interfacial interaction involves energy transfer and has very seldom been investigated as a mechanical phenomenon. Designing devices and instrumentation requires understanding the relation between mechanics and electronics with the latter serving as the signal transduction mechanism. Some questions left unanswered include:

• How are the electrical properties related to nanoscale mechanics?
• Can we manipulate the stress to control the properties?
• How can we fine tune biology, chemistry, and mechanical properties for actuation of devices?

Interfaces and interphases offer rich areas for investigating nanoscale mechanical manifestation of energy transfer. Solid-liquid interfaces and membrane-liquid interfaces transport and concentrate molecules, charge carriers, ions, dipoles, etc. This can result in mechanical phenomena that are yet to be fully investigated at the nanoscale.

Investigating the nanoscale motion at interfaces will lead to measurement and control of frictional forces. e.g., by imposing a mechanical periodic perturbation at the interface can control the frictional forces at nanoscale. The effect of charge density on frictional and flow properties is yet to be investigated. Creation of charge carriers at the interface using light can lead to the control of flow, viscous, and frictional properties.

It is now well established that adsorption of molecules on a surface can result in mechanical stress. Such stress can be manipulated using light, charge, and temperature leading us to a new paradigm in chemical speciation. Such direct translation of molecular recognition into nanomechanics offers opportunities in novel sensing devices, operation of nanoscale valves, nanofluidics, and operation of micro- or nanorobotic machinery. Development of such sensors and devices that capitalize on physical properties such as molecular impressions will revolutionize the chemical and biological sensors and biomedicine.

Theoretical modeling of large molecular structure is of great importance, for example, in the modeling of protein structure and folding, size and shape of proteins. Investigating interactions of large and small molecules at an observable scale require development of devices and structures at the same scale. Theoretical and computational modeling will significantly enhance experimental techniques, probe designs, and nanofabrication.