A new approach towards the Debye length challenge for specific and label-free biological sensing based on field-effect transistors

Abstract

A Meta-Nano Channel BioFET is demonstrated to decouple the electrostatics of the solution from the electrodynamics of the FET such that the Debye screening length can be electrostatically tuned to enhance the sensor output signal.

Specific and Label‐Free Sensing of Prostate‐Specific Antigen (PSA) from an Ultrasmall Drop of Diluted Human Serum with the Meta‐Nano‐Channel Silicon Field‐Effect Biosensor

“…The shape, size, and location of I DS is determined by the gates that control the depletion regions surrounding the readout current. [ 27 ] Schematically, V GB and V GR determine the vertical depletion regions (metal‐oxide‐silicon capacitors). V GL1 and V GL2 determine the lateral depletion regions ( p – n junctions).…”

Photo-Enhanced Chemo-Transistor Platform for Ultrasensitive Assay of Small Molecules

“…10,11 In addition, these technologies normally require labels, introducing additional contaminations that are involved in the detection system and interfere with the desired signals. 12 Some of them can monitor mono-or a few molecules; however, such high sensitivity relies on nanometersized transducers, tiny testing volumes, and ultrasmall recognition cross sections, inherently lacking the generality to monitor diverse small molecules in most cases. 13 Till now, a comprehensive methodology to monitor small molecules in an ultrasensitive, easily operable, and portable manner is lacking.…”

“…Small molecules refer to compounds with a molecular weight less than 1000 Da, some of which such as methylglyoxal (MGO), dopamine, thiamine, and sarcosine have trace contents down to the pM (1 pM = 10 –12 M) level in bio-fluids, yet play important roles in life activities. − Sensitive assay of small molecules is highly desired not only for biological and medical research but also for early diagnosis of diseases . Although assay technologies such as chromatography, spectroscopy, and electrochemistry , have been developed, they suffer from some disadvantages such as low sensitivity, costly instrumentation, small throughput, complicated sample preparation, lack of portability, or the need for well-trained operators. , In addition, these technologies normally require labels, introducing additional contaminations that are involved in the detection system and interfere with the desired signals . Some of them can monitor mono- or a few molecules; however, such high sensitivity relies on nanometer-sized transducers, tiny testing volumes, and ultrasmall recognition cross sections, inherently lacking the generality to monitor diverse small molecules in most cases .…”

A New Approach toward the Realization of Specific and Label‐Free Biological Sensing Based on Field‐Effect Devices

“…On the other hand, in a BioFET the gating of the channel is induced by the random and nonuniform distribution of binding events that affects the conducting channel only in specific locations immediately below the binding events, and we refer to this as a "local" effect [17] The second challenge is the well-known Debye screening length. [11][12][13][14][15][16][17][18][19][20][21][22] The Debye screening length is inversely proportional to the solution ionic strength. Moreover, the screening length at the solution-solid interface (λ s ) is smaller than the bulk value due to the inherent elevated ion concentrations at the solution-solid interface.…”

“…The second challenge is the well‐known Debye screening length. [ 11–22 ] The Debye screening length is inversely proportional to the solution ionic strength. Moreover, the screening length at the solution‐solid interface ( λ s ) is smaller than the bulk value due to the inherent elevated ion concentrations at the solution‐solid interface.…”