Immunoassay of prostate-specific antigen (PSA) using resonant frequency shift of piezoelectric nanomechanical microcantilever

Jeong Hoon Lee, Kyo Seon Hwang, Jaebum Park, Ki Hyun Yoon, Dae Sung Yoon, Tae Song Kim

Research output: Contribution to journalArticlepeer-review

148 Citations (Scopus)


We designed and fabricated the nanomechanical Pb(Zr0.52Ti 0.48)O3 (PZT) cantilever; we demonstrated a novel electrical measurement, under a controlled ambient temperature and humidity, for label-free detection of a prostate-specific antigen (PSA); and we achieved a detection sensitivity as low as 10 pg/ml. For the fabrication of our nanomechanical PZT cantilevers, we used composite layers of Ta/Pt/PZT/Pt/ SiO2 on a SiNx supporting layer for electrical self-sensing without external oscillators. This method allows PSA proteins to be detected via a simple electrical measurement of the resonant frequency change generated by the molecular interaction of the antigen (Ag) and the antibody (Ab). The resonant frequency shifted due to the specific binding of the PSA Ag to its Ab which is immobilized via calixcrown self-assembled monolayers on an Au surface deposited on a nanomechanical PZT cantilever. We determined the resonant frequency shift as the value of -172 Hz and -273 Hz, when the concentration of PSA Ag was 1 ng/ml, with the cantilever dimensions of 100 μm × 300 μm and 50 μm × 150 μm, respectively. Theoretical and experimental analysis suggests that the minimum detectable sensitivity for a resonant frequency shift due to a PSA Ag-Ab interaction depends on the dimensions of the nanomechanical PZT cantilever. These results also demonstrate that the experimentally measured resonant frequency shift is larger than that calculated theoretically due to the compressive stress of the PSA Ag-Ab interaction.

Original languageEnglish
Pages (from-to)2157-2162
Number of pages6
JournalBiosensors and Bioelectronics
Issue number10 SPEC. ISS.
Publication statusPublished - 2005 Apr 15
Externally publishedYes


  • Nanomechanics
  • PSA
  • PZT cantilever
  • Piezoelectric
  • Protein mass detection
  • Quantitative analysis

ASJC Scopus subject areas

  • Biotechnology
  • Biophysics
  • Biomedical Engineering
  • Electrochemistry


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