Many medical, forensic science, environmental and general scientific difficulties may be aided by the existence of suitable biosensors such as gene sensors, body fluid detection DNA sensors, disease detection DNA sensors etc. The sensor technology described here uses the conducting polymer polypyrrole (PPy) as both sensing element and transducer of sensing events. Stability and reproducibility are necessary characteristics of practical biosensors. The stability of polymers can be investigated using electrical impedance spectroscopy (EIS). This work discusses research focused towards creating a stable, reproducible sensor surface for oligonucleotide detection. The effect of electropolymerisation conditions (electropolymerisation method, solvent and electrolyte used), post-growth treatment (cycling and EIS experiments), and the sensing-environment conditions on sensor stability and applicability will be discussed.