Interdigital Capacitive Sensor Research Articles

Analytical evaluation of the interdigital electrodes capacitance for a multi-layered structure

The widespread use of interdigital electrodes in such applications as microwave filters, surface acoustic wave devices, electro-optic shutters as well as on chemical and biological sensing and even on the electrical and dielectric characterization of materials requires that we improve our description of their electrical performance. In this paper, we present new analytical expressions for the capacitance between the two comb electrodes of a periodic interdigital capacitive sensor, based on conformal mapping techniques. This proposed model is general and quite independent of the particular application and can be applied for any space and finger width as well as for any number of layers with different thickness and permittivity. The capacitance for a particular sensor configuration is a function of the dielectric permittivity of the materials, the fingers length and of two geometric non-dimensional parameters: (i) the ratio between the space and finger widths; (ii) the ratio between the thickness of the sensitive layer and the spatial sensor wavelength. Comparisons with previously published models as well as with experimental data and finite element analysis were made.

Acetylcholine Receptor-Based Biosensor

Abstract The acetylcholine (ACh) receptor protein isolated from Torpedo electric organ was incorporated into asolectin liposomes and immobilized noncovalently on the surface of a Planar Interdigitated Capacitive sensor to produce an ACh receptor-based biosensor. Capacitance of the biosensor, which was stable in buffered saline, increased rapidly when ACh was added. The response was dosedependent and specific for ACh, and the biosensor did not respond to six other neurotransmitters. Impure receptor preparations containing ACh esterase produced a smaller signal in response to ACh but showed enhanced response after inhibition of ACh esterase with diisopropylfluorophosphate. The competitive antagonist d-tubocurare, and the noncompetitive antagonist amantadine, inhibited the response of the biosensor to ACh, but a time-dependent recovery occurred upon perfusion with ACh. The irreversible antagonist α-neurotoxin inhibited the response and there was no recovery following perfusion with ACh. Thus, the pharmacolog...