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Biotechnology is in great need of low-cost intelligent biochips capable of massive parallel detection to be used in portable instrumentation.The advent of aptamer-based technology opened the doors to a new class of biosensor devices without the need of antibodies.Aptamers are synthetic DNA/RNA or peptide sequences that mimic the function of antibodies in binding a wide range of analytes.Aptamers have many advantages over antibodies due their ease of chemical modifications,surface immobilisation onto transducers and low cost.On the other hand,mature semiconductor technologies can be exploited for the development of biosensor arrays.In particular,field-effect transistors can be used for the development of arrays of potentiometric biosensors or as switching elements for other electrochemical biosensors.The coupling of semiconductor devices with aptamers leads to highly promising biosensors for biomedical diagnosis and environmental monitoring.Field-effect transistors(BioFETs)can be used as biosensing transducers either with a metal gate configuration where a biorecognition element is grafted to the gate(BioFET)or with the dielectric material exposed to the electrolyte,becoming sensitive to pH variations(ISFET).In both configurations,the FETs act both as transducer elements and as elements in a switching array.We have recently developed a range of aptamer-based BioFETs as well as a new application for ISFETs: monitoring protein phosphorylation in the presence of kinases,allowing the rapid high-throughput screening of a large number of kinase inhibitors,which can lead to the development of new drugs.The combination of field-effect devices with localised surface plasmon resonance on the same chip has been used for on-chip validation of the results.Electrochemical impedance spectroscopy(EIS)is a very promising technique,which can be easily expanded into arrays,e.g.using FETs as switching elements for easy,fast and on-chip sensor conditioning and readout.A particular area where EIS has great potential is on the detection of biomarkers using DNA aptamers.Upon aptamer-biomarker interaction there is a conformational change on the DNA,causing a change in the charge distribution and therefore on the EIS signal.We here exemplify the use of aptamers for the detection of prostate-specific antigen(a cancer biomarker).A careful choice of surface chemistries needs to be made for each type of sensing technique and each type of bioreceptor used,followed by a thorough characterisation of the biosensor under different conditions.Examples of different approaches will be presented both in terms of bioimmobilisation strategies and thorough characterisation in terms of sensitivity and specificity.The integration of different electrochemical and nanoplasmonic sensing techniques on a single chip can easily be achieved and examples will be given on how the engineering of the biolayer enables different sensing technologies to be implemented.The integration of the sensors with on-chip electronic circuitry and microfluidics is essential for the development of future device prototypes.