Introduction.- Chemistry of Conductive Solutions.- Biochemistry of Targets and Probes.- Target/Probe interactions.- Surface Immobilization of Probes.- Nano Technology to prevent Electron Transfer.- Bio/CMOS interface for Label-free Capacitance Sensing.- nanotechnology to enhance electron transfer.- Bio/CMOS interface in Constant Bias.-Bio/CMOS interface in Voltage Scan.- Appendix 1 - Basic Chemistry.- Appendix 2 - Basic Configurations of Operational Amplifiers.- Appendix 3 - The Fourier Theorem.- Appendix 4 - The Fourier and Laplace Transforms.