2.2 Detection principle,microsystem and proof of principle experiments
Gold microelectrodes on chip were used for the impedance analysis. The electrodes were produced with silicon micro fabrication technologies and included in a PDMS chamber. The electrodes were spaced 600 µm and the chamber volume was 36 nL(530 µm in width, 850 µm long and 80 µm deep)
Impedance spectra were collected at 50 frequencies logarithmically spaced between 1 KHz and 1 MHz, applying 100 mV excitation potential and 10 seconds pause at 0 mV between scans.
Bare electrodes were used for the analyses In such experimental condition the conductivity X is expressed as: