Quantum capacitance sensing

An apparatus for use in a sensing method for sensing a chemical substance, which apparatus comprises:

• an electrochemical spectrometer that comprises a working electrode, a counter electrode and a potentiostat, said working electrode comprising receptor moieties that are capable of binding to said chemical substance, wherein said working electrode comprises an electrode substrate functionalized with sensing elements whose electrochemical response to applied potentials is sensitive to the binding of said chemical substance to said receptor moieties, the sensing elements having a dimension of from 0.5 to 10 nm;
• a receiver configured to receive, from said electrochemical spectrometer, input data comprising a plurality of measurements of complex impedance, Z*, across a range of applied potentials;
• and
• a processor configured to (i) convert said plurality of measurements of Z* into a plurality of measurements of the real component of the complex capacitance, C′, at a selected frequency ω and/or the imaginary component of the complex capacitance, C″, at a selected frequency ω, and (ii) integrate said measurements of (a) C′, (b) C″, or (c) any combination of C′ and C″, at the selected frequency ω as a function of applied voltage to obtain an integrated measurement value.

A storage medium storing computer readable code for implementation by a computer or network of computers, the code, when implemented, causing the computer or network of computers to implement the steps of:

• obtaining, from an electrochemical spectrometer, input data comprising a plurality of measurements of complex impedance, Z*, across a range of applied potentials;
• converting said plurality of measurements of Z* into a plurality of measurements of the real component of the complex capacitance, C′, at a selected frequency ω and/or the imaginary component of the complex capacitance, C″, at a selected frequency ω;
• and
• integrating said measurements of (a) C′, (b) C″, or (c) any combination of C′ and C″, at the selected frequency ω as a function of applied voltage to obtain an integrated measurement value.