Smart devices

Molecular programming of intelligent responses in sol-gels

Professor Bakul Dave at the department of Chemistry and Biochemistry, Southern Illinois University has developed a multidisciplinary approach based on integration of ideas from several disciplines of pure and applied sciences such as chemistry, biochemistry, spectroscopy, and materials science to synthesize sol-gel made materials with well defined structural, functional, and operational response. Chemical synthesis of integrated molecular systems is the key to develop molecule-based devices. In seeking breakthroughs towards this capability, the strategy developed by the Dave's research team is to incorporate suitable response active molecules within an inorganic matrix to provide the rigidity and stability necessary for device applications. An approach based on structural integration of suitable biomolecular entities in a porous solid state matrix such as sol-gel derived oxides is currently being pursued in his lab to generate composite materials. Such an approach enables them to tailor and engineer the properties and functional response of a material which are determined by the dopant molecule. More importantly, it also provides means to design materials from a molecular perspective, and these materials are used as molecular sensors and transducers. 

Professor Dave presented recent progress in this field at the XI Int. Workshop on Glasses, Ceramics, Hybrids and Nanocomposites from Gels. His presentation  focused on the design and assembly of novel sol-gel—derived materials and devices that are capable of detecting and responding to changes in their environment.  The ability to sense and respond to environment is a basic requirement of intelligence, and these materials constitute a novel class of "smart" glasses. For design of advanced material, the advantage of using sol-gel—derived materials is that the parent silica glass is optically transparent, electrically insulating, functionally inactive, and operationally nonresponsive. Therefore, by selectively integrating specific response-active molecules into the glass, it is possible to introduce desired optical, electronic, functional, or operational properties in a modular fashion.This structural-functional modularity allows a sequential modification of the parent material and facilitates rational design of new advanced materials with a degree of control over their functional properties. In order to be able to elicit smart responses, our approach is based on modification of silica glasses with specific functional groups to obtain porous materials wherein noncovalent interactions can be controlled selectively by means of adjusting external physicochemical variables. Vital criteria for generating stimuli-induced dynamic responses include the occurrence of a bulk volume transition, which is initiated by alteration of noncovalent interactions within a material, and subsequent expulsion/intake of water. Recent studies show that by using organic functional groups containing a proper balance of hydrophilic and hydrophobic residues as modifiers, it is possible to design a series of sol-gel—based environmentally-sensitive materials.