Micromechanical cantilever as an ultrasensitive pH microsensor

R. Bashir, J. Z. Hilt, O. Elibol, A. Gupta, N. A. Peppas

Research output: Contribution to journalArticlepeer-review


We report on a pH sensor with ultrahigh sensitivity based on a microcantilever structure with a lithographically-defined crosslinked copolymeric hydrogel. Silicon-on-insulator wafers were used to fabricate cantilevers on which a polymer consisting of poly(methacrylic acid) (PMAA) with poly(ethylene glycol) dimethacrylate was patterned using free-radical UV polymerization. As the pH around the cantilever was increased above the pK a of PMAA, the polymer network expanded and resulted in a reversible change in surface stress causing the microcantilever to bend. Excellent mechanical amplification of polymer swelling as a function of pH change within the dynamic range was obtained, with a maximum deflection sensitivity of 1nm/5×10-5ΔpH.

Original languageEnglish (US)
Pages (from-to)3091-3093
Number of pages3
JournalApplied Physics Letters
Issue number16
StatePublished - Oct 14 2002
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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