Fabrication and Characteristics of a Field Effect Transistor-Type Charge Sensor for Detecting Deoxyribonucleic Acid Sequence

Possibilities and limitations of label-free detection of DNA hybridization with field-effect-based devices

“…The inherent miniaturization of such devices and their compatibility with advanced microfabrication technology can make them very attractive for DNA diagnostics. Therefore, in recent years, several attempts have been made to detect DNA by its intrinsic molecular charge using field-effect devices, like capacitive electrolyte-insulator-semiconductor (EIS) and field-effect transistor (FET) structures [5][6][7][8][9][10][11][12][13][14][15][16]. A DNA-FET is obtained by immobilizing well-defined sequences of ssDNA onto a field-effect transducer, which could convert the specific recognition process between the two complementary DNA single strands into a measurable signal.…”

Covalent molecular functionalization of diamond thin-film transistors

“…While widely used substrates such as silicon, SiO 2 , and gold can be functionalized with a variety of organic molecules, these surfaces ultimately suffer from degradation in physiological environments [10][11][12][13][14][15][16][17][18].…”

Chemical and Biological Field‐Effect Sensors for Liquids—A Status Report

“…Therefore, in recent years, a considerable research effort has been devoted to the label-free electronic detection of biomolecules (DNA, proteins) by their intrinsic molecular charge using FEDs. [45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60] In most cases, the experimentally observed sensor response is interpreted in a way that during the binding event (hybridization of immobilized single-strand DNA (ssDNA) cDNA ssDNA p-Si with its complementary target molecule (cDNA); see Figure 2) the charge associated with the target molecule effectively changes the charge applied to the gate of the FED. As a result, the operating characteristics of the FED, that is, the flat-band voltage and capacitance of the EIS sensor or the threshold voltage and drain current of the FET device, will also change.…”

“…Furthermore, it is not understandable, why a much higher signal has been observed for a sensor with a less density of immobilized ssDNA (1.45 V with 3.8 × 10 8 molecules/cm 2 49 ) compared to a sensor with a densely packed ssDNA (3 mV with 5 × 10 13 molecules/cm 2 45 ). Or to give a second example, it is not understandable, what the reason is for the much higher biosensor signals, which are observed when floating-gate transistors [47][48][49][50] or devices without a necessary reference electrode 46,47,49 have been used; or, why a DNA-FET without a reference electrode can deliver a reliable sensor signal? 46,47,49 Field-effect sensors are basically surface-charge (potential) measuring devices and are principally able to measure the charge of adsorbed macromolecules or the charge change due to a hybridization event.…”

“…Or to give a second example, it is not understandable, what the reason is for the much higher biosensor signals, which are observed when floating-gate transistors [47][48][49][50] or devices without a necessary reference electrode 46,47,49 have been used; or, why a DNA-FET without a reference electrode can deliver a reliable sensor signal? 46,47,49 Field-effect sensors are basically surface-charge (potential) measuring devices and are principally able to measure the charge of adsorbed macromolecules or the charge change due to a hybridization event. At the same time, however, owing to the so-called counterion screening effect and the nonideality of the molecular layer, the realization of these devices for a direct electrostatic detection of charged macromolecules by their intrinsic molecular charge in relatively high-ionic-strength solutions such as physiological solutions is problematic.…”