PHEMA functionalization of gold nanoparticles for vapor sensing: Chemi-resistance, chemi-capacitance and chemi-impedance

A chemical sensor fabricated from gold nanoparticles and poly(2-hydroxyethyl methacrylate) (PHEMA) is presented and its chemi-resistive, chemi-capacitive and chemi-impedance performance is investigated. Detection of humidity and ethanol in the range of 2000–20,000 ppm has been made possible in all the above cases. The sensor was fabricated following a two step process utilizing ink-jet printing to deliver both nanoparticles and PHEMA on oxidized silicon substrates: first a layer of nanoparticles has been delivered on top of gold interdigitated electrodes followed by the successive deposition of PHEMA polymer. By controlling several key design parameters such as nanoparticle size, number of ink-jet printed gold nanoparticles and electrode spacing, the fabrication of chemical sensors with different sensing response and linearity is possible.