Fig. 4: Dependance of the biosensor sensitivity on the ionic strength of the sensing medium for Non-Faradaic EIS detection.
From: Label-free impedimetric immunosensor for point-of-care detection of COVID-19 antibodies
Non-Faradaic EIS detection of selective binding of antibodies to the S-proteins immobilized on the recognition layer of the impedimetric immunosensor comparing the effect of PBS concentration on the device sensitivity using MUOH- and APTES-modified IMA. (a, e)Bode plot of experimental EIS spectra before (black dash line) and after (redline) incubation with serum sample, (b, f) EIS spectra plotted in expanded scale to show the impedance change, (c, g) plot of ΔZ (ΔZ = ZSerum– Zbgr) versus frequency, (
) COVID-19 positive serum, (
) COVID-19 negative serum, (
) 1% milk blank samples, solid lines are drawn to guide the eyes, and (d, h) plot of the detection signal ΔZRel % (ΔZRel % = ΔZ/Zbgr × 100).Plots (a–d) and (e–h) correspond to EIS measurements made in 1× PBS or 0.001× PBS solution at pH 6.5, respectively.
