“…enzyme-linked immunsorbent assay, particle-based flow cytometric assays, electrochemical measurements based on impedance and capacitance, electrical measurement of micro-cantilever resonant frequency change, conductance measurement of semiconductor nanostructures, gas chromatography, ion chromatography, high density peptide arrays, laser scanning quantitative analysis, chemiluminescence, selected ion flow tube, nanomechanical cantilevers, bead-based suspension microarrays, magnetic biosensors and mass spectrometry have been employed [5,59,69,72,185,190]. However, depending on sample condition, these methods show variable results in terms of sensitivity for some applications and therefore may not meet the requirements for a hand-held biosensor [191].…”