Semiconductor Device-Based Sensors for Gas, Chemical, and Biomedical Applications

Bioaffinity Sensors Based on MOS Field-Effect Transistors 225

© 2011 by Taylor & Francis Group, LLC

Because these parameters successfully explain the pH response of an ISFET in contact with

the NaCl solution, it is appropriate to assume that the Helmholtz layer thickness is close to 0.4 nm

[27]. The amine binding has been included in models of BioFETs based on planar sensors [27] and

nanowires [28]. But if the nitride surface oxidizes in water, the surface will be covered by hydroxyl

groups and the site-binding model for a relatively poor oxide surface could apply.

6.2.3  molecules on the oxide surface

Figure6.5 shows schematically the molecules ...