Polymer-based materials to be used as the active element in microsensors: a scanning force microscopy study

Area of Science:

• Materials Science
• Chemical Sensing
• Nanotechnology

Background:

• Polymer-based materials are utilized as active sensing elements in chemiresistor devices.
• Polymer swelling upon exposure to gaseous analytes causes measurable changes in composite material conductivity.
• Carbon black is incorporated into nonconducting polymers to create conductive composites for sensing applications.

Purpose of the Study:

• To investigate microstructural changes in carbon-polymer composites using scanning force microscopy (SFM).
• To analyze the response of poly (isobutylene) (PIB), poly (vinyl alcohol) (PVA), and poly (ethylene-vinyl acetate) (PEVA) to various analytes.
• To introduce and describe a novel microsensor based on piezoresistive microcantilever technology.

Main Methods:

• Utilized scanning force microscopy (SFM) with phase-contrast imaging (PI) to observe surface microstructural changes.
• Exposed polymer composites (PIB, PVA, PEVA) to vapor-phase analytes: hexane, toluene, water, ethanol, and acetone.
• Developed and described a new piezoresistive microcantilever-based microsensor for direct measurement of polymer volume changes.

Main Results:

• Observed changes in carbon nanoparticle distribution on polymer surfaces upon analyte exposure.
• Demonstrated that some observed microstructural changes were reversible upon analyte removal at the SFM measurement scale.
• Introduced a new microsensor technology that directly measures polymer volume changes via piezoresistive microcantilevers.

Conclusions:

• SFM provides insights into microstructural responses of polymer composites to analytes.
• Piezoresistive microcantilever sensors represent a promising alternative to traditional chemiresistors for gas sensing.
• The new microcantilever devices may offer advantages in direct, sensitive detection of analyte-induced polymer volume changes.