Implantable electrode

An implantable electrode having an electrically conductive porous material comprising metal carbide, metal nitride, metal carbonitride, metal oxide or metal oxynitride and one or more coating layers on a surface of said material, said coating layer or at least one of said coating layers being for contact with body tissue when the electrode is implanted, and each said coating layer being an electrically conductive layer of polymer having a polypyrrole polymeric backbone or polythiophene polypyrrole substituted at the 1-position (N-atom) or the 3-position with a substituent —A-X or an allyl-terminated pendent group, or is a polythiophene substituted at the 3-position with a substituent —X, —A-X, or an allyl-terminated pendent group, wherein:

• A is alkylene or alkenylene of 1-6 carbon atoms;
• X is —COOH, —COO-, —COOR′, —CONH2, —CONHR′, —CON(R′)2, —COR′, —F, —Cl, —Br, —I, —CN, —NO2, —OH, —OR′, —SH, —SR′, —O-CO-R′, —NH2, —NHR′, —NH(R′)2, —N(R′)3+, —NH-CO-R′, —NH-CO-H, —NR′-CO-R′, —NR′-SO2H, —NR′-SO2R′, —SO2R′, —OSO2R′ or —OPO;
• R′ is alkyl or alkenyl of 1-6 carbon atoms;
• and
• the allyl-terminated pendent group comprises —O-CH2-CH=CH2, —S-CH2- CH=CH2, —S(=O)-CH2-CH=CH2, —Se-CH2-CH=CH2, or —Se(=O)-CH2-CH=CH2.