A single-use bioreactor, comprising: a contacting-type conductivity sensor comprising: an electrically insulative thermoplastic body; a plurality of conductive electrodes (12, 14, 16, 18) disposed in the thermoplastic body, wherein each electrode (12, 14, 16, 18) being constructed of thermoplastic compound and co-extruded with the thermoplastic body; wherein the insulative thermoplastic body and a thermoplastic portion of the plurality of electrically conductive thermoplastic electrodes (12, 14, 16, 18) being formed of the same thermoplastic compound without seals or material interfaces therein, a bioreaction chamber configured to hold a specimen; wherein the contacting-type conductivity sensor is mounted on a plastic wall within the bioreaction chamber by a bond such that the electrodes (12, 14, 16, 18) of the contacting-type conductivity sensor are configured to contact the specimen, and wherein the bond liquid-tightly seals an aperture within the wall of the bioreaction chamber, and wherein the aperture allows conductors (60, 62, 64, and 66) that are coupled to electrodes (12, 13, 16, 18) to pass therethrough. a contacting-type conductivity sensor comprising: an electrically insulative thermoplastic body; a plurality of conductive electrodes (12, 14, 16, 18) disposed in the thermoplastic body, wherein each electrode (12, 14, 16, 18) being constructed of thermoplastic compound and co-extruded with the thermoplastic body; wherein the insulative thermoplastic body and a thermoplastic portion of the plurality of electrically conductive thermoplastic electrodes (12, 14, 16, 18) being formed of the same thermoplastic compound without seals or material interfaces therein, an electrically insulative thermoplastic body; a plurality of conductive electrodes (12, 14, 16, 18) disposed in the thermoplastic body, wherein each electrode (12, 14, 16, 18) being constructed of thermoplastic compound and co-extruded with the thermoplastic body; wherein the insulative thermoplastic body and a thermoplastic portion of the plurality of electrically conductive thermoplastic electrodes (12, 14, 16, 18) being formed of the same thermoplastic compound without seals or material interfaces therein, a bioreaction chamber configured to hold a specimen; wherein the contacting-type conductivity sensor is mounted on a plastic wall within the bioreaction chamber by a bond such that the electrodes (12, 14, 16, 18) of the contacting-type conductivity sensor are configured to contact the specimen, and wherein the bond liquid-tightly seals an aperture within the wall of the bioreaction chamber, and wherein the aperture allows conductors (60, 62, 64, and 66) that are coupled to electrodes (12, 13, 16, 18) to pass therethrough. wherein the contacting-type conductivity sensor is mounted on a plastic wall within the bioreaction chamber by a bond such that the electrodes (12, 14, 16, 18) of the contacting-type conductivity sensor are configured to contact the specimen, and wherein the bond liquid-tightly seals an aperture within the wall of the bioreaction chamber, and wherein the aperture allows conductors (60, 62, 64, and 66) that are coupled to electrodes (12, 13, 16, 18) to pass therethrough.