SH-SAW-based sensor for heavy metal ion detection

In this study, a shear horizontal mode surface acoustic wave (SH-SAW) sensor, was designed and fabricated for the detection of heavy metals. The SH-SAW sensor was photolithographically fabricated by patterning gold (Au) interdigitated electrodes (IDE) and reflectors on the surface of a 64° YX-LiNbO
₃
based piezoelectric substrate. A flow cell, with a reservoir volume of 3 μl, which employs inlet and outlet ports for the microfluidic chamber and polydimethylsiloxane (PDMS) based microfluidic channels, was also designed and fabricated using acrylic material. Phenol and naphtho[2,3-a]dipyrido[3,2-h:2'3'-f] phenazine-5,18-dione (QDPPZ) were employed as the sensing layers for mercury and nickel ions, respectively. The frequency based response of the SH-SAW sensor demonstrated picomolar level detection for mercury nitrate (Hg(NO
₃
)
₂
) and nickel nitrate (Ni(NO
₃
)
₂
).