A novel description of ISFET sensitivity with the buffer capacity and double-layer capacitance as key parameters

Abstract

The pH sensitivity of ISFETs arises from interactions of protons with ISFET gate surface sites. This sensitivity is described by a new simpler model with the intrinsic buffer capacity and the differential capacitance as key parameters. The obtained expression is independent of the models used for the chemical surface equilibria and the charge profile in the solution. The general expression for the sensitivity is elaborated using the site-binding theory and the Gouy-Chapman-Stern theory. The relatively high sensitivity of Ta?O, ISFETs is explained using this elaborated theory. It is shown that the electrolyte concentration has almost no influence on the sensitivity of Ta,O, ISFETs.

Interaction of colloidal nanoparticles with their local environment: the (ionic) nanoenvironment around nanoparticles is different from bulk and determines the physico-chemical properties of the nanoparticles

“…Additionally, table 1 provides literature for a more detailed study, sorted by the metals (Au, Ag) studied. [107][108][109][110][111]. At low pH, the surface can be charged positively by the adsorption of protons (MOH 2 þ ), whereas it will be negatively charged at high pH owing to depletion of protons (M-O 2 ).…”

Specific and label-free femtomolar biomarker detection with an electrostatically formed nanowire biosensor

“…The pH sensitivity of the device was calculated to be 43 mV dec À1 , where the maximum theoretical value for the pH sensitivity of the SiO 2 gate dielectric at this range of pH is 47-50 mV dec À1 . 22 A real-time, specific and labelfree detection of 10 pg ml À1 (B340 fM) cTnI is demonstrated in Figure 3a. The measurement was performed with narrow W eff (V Gj ¼ À2 V), and V REF was selected to provide the highest g m according to the I DS -V REF plot.…”

“…This fact implies that the interplay between sensing, charge carrier distribution and the confinement potential is inherently different in comparison to a SiNW or a double-gate nanowire (see the Supplementary Information for device simulations of the EFN parabolic potential vs the step-like potential in the SiNW and the double-gate nanowire). Additionally, degradation in the performance of SiNW-based devices due to metal catalysts and non-uniform dopant distribution [19][20][21][22] does not exist in EFN biosensors because EFNs are electrostatically shaped inside singlecrystalline silicon. The EFN configuration allows the channel to be sufficiently removed from the Si/SiO 2 interface, 23 which is the dominant noise source in SiNWs [24][25][26][27][28][29] as well as in inversion-type planar devices 30 (and in the double-gate nanowire, where the conduction is due to the formation of an inversion layer at the silicon/SiO 2 interface).…”

Electrical characterization of high performance, liquid gated vertically stacked SiNW-based 3D FET biosensors

“…The surface potential change Δφ0 with respect to a pH value change� 0 � has been derived from the site-binding (SB) and Gouy-Chapman-Stern (GCS) model [9][10][11][12][13], Eq. 5:…”