ABSTRACTOrganically modified silica gels and dye-doped silica gels have been
patterned into micrometer-scale structures on a substrate using micro
molding in capillaries (MIMIC). This approach is from a class of elastomeric
stamping and molding techniques collectively known as soft lithography. Soft
lithography and sol-gel processing share attractive features in that they
are relatively benign processes performed at ambient conditions, which makes
both techniques compatible with a wide variety of organic molecules,
molecular assemblies, and biomolecules. The combination of sol-gel and soft
lithography, therefore, holds enormous promise as a tool for
microfabrication of materials with optical, chemical, or biological
functionality that are not readily patterned with conventional methods. This
paper describes our investigation of micro-patterned organic-inorganic
hybrid materials containing indicator dyes for microfluidic sensor
applications. Reversible colorimetric pH sensing via entrapped reagents is
demonstrated in a prototype microfluidic sensor element. Patterned
structures range from one to tens of micrometers in cross-section and are up
to centimeters in length. Fundamental chemical processing issues associated
with mold filling, cracking and sensor stability are discussed.
Orientation and spectral properties of two stilbazolium merocyanine dyes in stretched and unstretched polyvinyl alcohol films.