Biochip Development Pathway (1cm×1cm). Cut from 0.5mm Si (100) wafer.

SiO2 electrically insulating layer (~ 400 nm)

Substrate Modification

Silicon Substrate

1) Thermal Oxidation 24 hrs at 950°C Wettability AFM, Ellipsometry 2) Aerosol Pyrolysis

SnO2 layer doped with Sb (ATO) Thickness and rougness depend of time deposition.

with 0.2 Mole/L SnCl4 and SbCl3 in methanol solution. Molar solution percentage Sb is set at 2% of Sn. Time of deposition varied between 30 sec et 20 min to obtain different layer thicknesses of SnO2. (~100nm to 1µm)

Wettability AFM, SEM Raman Spectroscopy 3) Hydroxilation Silanisation

Substrate Fonctionalisation Wettability AFM Raman Spectroscopy

Polymer layer: ATPES a few nanometres

4) DNA Grafting Hybridization detection

Hybridization DNA Probe/Target

DNA Immobilisation Fluorescence Hybridization Détection

DNA target Molecule with fluoresecente labelling

Probe DNA Molecules grafted Adhesive Polymer layer. SiO2 insulating inter-layer

SnO2 deposited conductive layer