Table 1. Classification and performance characteristics of biosensors for infectious disease detection.

Type	Specification	Advantages	Disadvantages	References
Electrochemical
Voltametric	Measures current while varying the potential over time also includes Differential pulse voltammetry (DPV) and Cyclic voltammetry (CV)	These systems offer high sensitivity, low cost, portability, and fast response with minimal sample use	Stable surface modifications and complex protocols are needed, and biological components may limit performance and need complex indicators	1
Amperometric	Measures current at constant potential, proportional to electroactive species concentration	Facilitates the measurement of analytes. Retains the general benefits of electrochemical biosensors	Shares general disadvantages: complexity in production, signal interference, and potential enzyme inhibition	1, 4 and 50
Potentiometric	Measures potential between electrodes at zero current, reflecting analyte concentration or activity	Good selectivity, sensitive, stable reference systems, low power consumption, noninvasive potential	Limited to ions and certain analytes, affected by ionic strength or matrix composition, production and calibration complexity	1, 4 and 5
Impedimetric	Measures impedance of electrode-solution interface (e.g., Electrochemical impedance spectroscopy (EIS))	Label-free detection allows sensitive, real-time biomolecular analysis and is suitable for miniaturization and adaptable use	Temperature and matrix effects, complex interpretation, surface modification required and exposure to environmental noise	1, 18 and 51
Conductometric	Measures changes in conductivity near the electrode due to biochemical reaction	Easy setup, rapid feedback, wide detection range, ideal for small sample sizes and complex matrices	Requires signal amplification, limited specificity, temperature and pH dependent	1 and 5
Other types (Organic electrochemical transistor (OECT), photoelectrochemical, and electrochemiluminescent sensors)	Each uses specialized electrical or light-based detection principles	Enhanced sensitivity, integration with optical/electronic systems, suitable for multiplexed detection and portable formats	Integration and design complexity, high cost of specialized parts, need for advanced production	1
Optical
Surface plasmon resonance (SPR)	Measures refractive index shifts at a metal–liquid interface due to biomolecular binding	High sensitivity, real-time monitoring, label-free, kinetic, and affinity analysis possible	Expensive instrumentation, limited to surface interactions, requires stable surface functionalization, sensitive to temperature and bulk refractive index changes	52
Ellipsometry	Measures changes in light polarization upon binding, precise surface analysis	Ultrasensitive to thin layers, label-free, suitable for surface binding studies	Requires clean, reflective surfaces, complex data interpretation	53
Absorbance/reflectance	Measures light absorbed/reflected due to analyte–enzyme/color interaction	Simple setup, cost-effective, compatible with basic lab equipment	Lower sensitivity, prone to interference, limited dynamic range	54
Scanning angle reflectometry (SAR)	Measures angle-dependent reflectance to analyze refractive index and layer thickness	High precision for layer thickness and surface concentration, label-free	Needs angular scanning setup, less portable, sensitive to vibrations	55
Chemiluminescence/luminescence	Detects light emitted from enzyme-catalyzed chemiluminescence or bioluminescent reactions	Very high sensitivity, low background noise, does not require excitation source	Limited enzyme stability, single-use, reagent dependent, short-lived signal duration	56
Fluorescence resonance energy transfer (FRET)	Monitors energy transfer between two fluorophores in close proximity	Excellent for molecular interaction mapping, real-time detection, high spatial resolution	Requires dual labeling, distance dependent, expensive reagents, photobleaching of fluorophores affects performance	57
Total internal reflection fluorescence (TIRF)	Uses evanescent field to excite fluorophores near surface only	High surface specificity, low background noise, excellent for membrane or surface studies	Only detects events near surface (∼100–200 nm), requires precise optical alignment	58
Optical waveguide light mode spectroscopy (OWLS)	Measures refractive index changes at waveguide surface	Real-time, label-free, suitable for kinetic and concentration measurements	Requires waveguide integration, niche applications, costly instruments	59
Interferometry (Mach–Zehnder interferometer, biolayer interferometry)	Measures phase shifts due to biomolecular binding on surface	Real-time, label-free, highly sensitive, suitable for kinetic profiling	Sensitive to temperature fluctuations and optical drift, requires stable operating environment	60 and 61
Piezoelectric
Bulk acoustic wave (BAW) (includes QCM, TSM, PQC)	Utilizes shear or longitudinal acoustic waves that propagate through the piezoelectric substrate; binding of biomolecules induces a frequency shift proportional to mass	High sensitivity to mass changes, real-time and label-free detection, suitable for biochemical liquid samples	Fragile at high frequency, sensitive to viscosity and temperature, requires surface functionalization	62, 63 and 43
	QCM: measures changes in resonance frequency on crystal surface
	TSM: detects changes through shear vibration, suited for liquids
	PQC: variant of QCM using AT-cut crystals, often interchangeable in biosensing. Used interchangeably with QCM in biosensing literature due to shared operational principles
Surface acoustic wave (SAW)	Surface-propagated acoustic waves interact with biomolecules on the sensor surface, changes in wave velocity/attenuation indicate binding	Extremely sensitive to surface interactions, fast response time, ideal for small molecule/pathogen detection, label-free	Sensitive to ambient temperature and humidity, complex and costly fabrication, limited robustness	62