This lecture covers the definition and working rationale of biosensors and electronic biochips, focusing on the detection of molecules on surfaces, examples of biochips, features describing a biosensor, output-measurand relationship, sensitivity, calibration curve, limit of detection, resolution, analyte selectivity, selectivity-specificity, prevention of non-specific adsorption, repeatability-reproducibility, hysteresis, precision-accuracy, sensor characterization, overload characteristics, and ambient conditions. The instructor discusses the tools used for bioanalytics, such as measuring physiological parameters and quantifying DNA/RNA content in samples, as well as advanced platforms like microarrays and microcantilevers.