Mobile electrochemical detector has been developed to use in the out-of-laboratory for aiming to on-site testing. Printable electrodes have advantages in mass productive and disposable biosensor applications. Electrochemical DNA detection has been originally developed without immobilization of DNA onto electrodes. PCR process can be monitored in real time and applied to detection of actual targets such as pathogens like Salmonella, E.coli O-157 and Flu virus, genetic modified organism, origin of meats and so on. Microfluidic PCR and RT-PCR chips were useful for rapid detection with our electrochemical DNA sensor method. Gold nanoparticle-antibody can be linked with new electrochemical imunoassay as GLEIA (gold linked electrochemical immunoassay). High sensitive detection of human chorionic gonadotropin (0.36 pg/mL) and insulin (0.1 ng/mL) were reported. Smartphone camera was also applied to detection of immunoteststrip and elecrochemical luminescence(ECL).