Table 3 Comparison of performance indices of different sensors.
From: Theoretical analysis of MWCNT and MXene/High-k pH BioFET sensors for biomedical applications
Sensor type | Working principle | Typical detection range | Sensitivity | Limit of detection (LOD) | Stability and challenges | Relevance to biomedical use |
|---|---|---|---|---|---|---|
Potentiometric ISFET36 | Measures gate potential change due to H⁺ ion concentration | pH 2–12 (reliable in ~ 6–8 clinically) | Near-Nernstian (~ 59 mV/pH) | ~ 0.05–0.1 pH | Good, but subject to drift and biofouling | Widely used; simple, label-free, but can suffer interference |
Amperometric37 | Measures current from redox reactions at electrode surface | Narrow, depends on redox couple | High, but reaction-specific | ~µM ion concentration equivalent | Affected by by-products and electrode fouling | Limited direct use for pH; more suited for metabolites |
Impedancemetric38 | Monitors impedance/capacitance change at electrode–electrolyte interface | Broad, but matrix-dependent | Very high (sub-Nernstian precision) | < 0.01 pH in optimized systems | Sensitive to noise and electrode polarization | Promising, but less mature for continuous pH monitoring |
Proposed BioFET | Bioelectronic extension of potentiometric ISFET; channel current modulated by surface potential | pH 5–9(covers biomedical range ~ 6–8) | Enhanced (~ 65 mV/pH using MXene/MWCNT high-k dielectric) | < 0.05 pH (estimated) | Improved stability due to high-k dielectric and hydrophilic MXene; robust against interference | Highly relevant: non-invasive, patch-based pH monitoring in sweat, saliva, ISF |
