The emerging electrochemical antimicrobial susceptibility testing draws inspiration from the established gold standard AST techniques. The detection principles underlying these methods rely on the monitoring of analyte changes that occur at the interface between the analyte and substrate, facilitated by Electrochemical Impedance Spectroscopy, Cyclic Voltammetry, Square Wave Voltammetry, Pulsed Voltammetry, etc., A central classification scheme that distinguishes between Faradaic and non-Faradaic currents serves to differentiate among these sensors based on the principle that governs their operation and measurement. In general, phenomenon that occurs at the interface between metal and solution involves the transfer of charges or electrons, which can lead to oxidation or reduction. This type of reaction is subject to Faraday's law, which states that the amount of chemical reaction that results from the flow of current is directly proportional to the amount of electricity passed. Because of this fundamental relationship, such reactions are classified as faradaic processes. However, it is important to note that under certain conditions, there may be a range of potentials at the electrode-solution interface where no charge-transfer reactions occur. This phenomenon is known as the "overpotential" or "overvoltage" region, where the electrode potential is too high or too low for the charge transfer reaction to occur. In this region, the electrode does not contribute to the electrochemical reaction, and the reaction is controlled by other factors such as mass transfer or chemical reaction kinetics. This is because these reactions may be thermodynamically or kinetically unfavourable. Thus, the occurrence of faradaic processes is not an inevitability, but rather is contingent on the specific conditions and properties of the system under investigation. The Non-faradaic processes are chemical reactions or phenomena which occur at the interface between an electrode and a solution during an electrochemical reaction, yet they do not entail the transference of charge or electrons across the interface. Instead, such processes implicate changes in the structure of the interface, alongside the adsorption and desorption of species onto or from the electrode surface. Examples of non-faradaic processes encompass adsorption and desorption, diffusion, conformational changes, and capacitive charging. It is imperative to duly consider non-faradaic processes during electrochemical experiments, for they may wield a notable influence upon the behaviour of the cell. Although non-faradaic processes do not entail the transfer of charge, they may still affect the kinetics of the faradaic reaction and the overall behaviour of the cell. Thus, it is essential to take into account the effects of nonfaradaic processes on the overall behaviour of the electrochemical cell, even in instances where only non-faradaic processes are extant. This may simplify the analysis of the cell's behaviour. Proceeding onwards, during an electrochemical experiment, a solution houses a working electrode and a reference electrode. An external power supply is employed to alter the potential difference between these electrodes. This variation in potential can facilitate the transference of electrons across the interfaces between the electrode and solution, thus producing a current flow in the external circuit. The number of electrons that are transferred is directly linked to the degree of chemical reaction transpiring at the electrode. The presence of bacteria can exert an influence upon charge transfer, mass transfer, diffusion and redox reactions transpiring at the solution and electrode interface . These effects may consequently impact the rate of electron flow and ultimately manifest within the resultant current-potential curve. In biological systems, the flow of electrons oftentimes correlates with metabolic processes and thereby plays an integral role in the functioning of microorganisms. Through a thorough comprehension of the association between charge transfer reactions and the resulting current-potential curve, valuable insights may be collected regarding the interplay between bacteria and their surrounding environment. Such insights serve as pivotal factors towards comprehending the involvement of microorganisms in biogeochemical cycling and towards designing novel methodologies for bioremediation. In the present review, we direct our attention towards assessing antimicrobial susceptibility testing in relation to these underlying principles. The magnitude of electron flow, or current, is quantified in units of amperes (A), with one coulomb of charge per second being equivalent to one ampere. Through plotting current as a function of potential, a current-potential (i vs. E) curve can be generated. This curve conveys insightful details concerning the reactions taking place at the interface of the electrode and solution. Proper comprehension of these curves is fundamental to electrochemistry, much like the comprehension of ATP utilization is a vital concept in comprehending biological systems. Therefore, to comprehend the behaviour of microorganisms in the electrochemical cell, one must bear in mind that electrochemical behaviour is governed by several parameters, including electrode potential (E), current (I), concentration (C), electrode area, mass transfer, and electrode geometry. These parameters can be controlled, or one or two parameters can be kept constant to monitor the behaviour of the electrochemical cell due to the analyte, bio entities such as mammalian cells, or in our case microorganisms. Phenotypic approaches have a rich history in classical microbiology as a means to determine the antibiotic susceptibility of bacterial strains. Such approaches are grounded in the culture of bacteria on a suitable medium, which is subsequently observed at a later stage to ascertain the bacteria's response to specific antibiotics. Nonetheless, advances in microsystems engineering and lab-on-a-chip technologies have surpassed the limitations of traditional agar plate or liquid culture methods, allowing for more sensitive probing of bacterial growth. As a result of these technological advancements, a broad range of sensor technologies with varying degrees of sample or microfluidic sample handling and integration have emerged. The development of such diverse sensor technologies has paved the way for a promising research field that investigates the use of electrochemical approaches to determine antibiotic susceptibility. These approaches typically entail measuring the changes in the electrical signals or properties of bacterial cells as they grow and metabolize in the presence of antibiotics, thereby enabling the rapid determination of antibiotic susceptibility, thus we will cover herein their advancement in techniques in this review. A.C. Ward et. al ., developed a technique with the use of electrochemical impedance spectroscopy (EIS) to determine antimicrobial susceptibility testing (AST). due to the high sensitivity of EIS, it is well suited to measuring AST and monitoring biofilm formation. The article discusses two distinct approaches to bacterial detection and analysis. Firstly, the use of a sensor to detect S. aureus in chronic wound infections is proposed. The sensor operates based on the electrochemical properties of wound exudate, which are similar to fetal calf serum, allowing for rapid detection of the bacteria in just 30 minutes. Additionally, efforts have been made to reduce the cost of the sensor by minimizing the amount of substrate and using conductive ink. Following this, Stuart Hannah et al presents(Figure ) a novel approach for determining antibiotic susceptibility by modifying an electrode surface with agarose gels. The hydrogel interface between the electrode and the electrolytes was generated using the common polysaccharide agarose, which has a porous nature. They were able to use this method to detect differences in susceptibility within just 45 minutes, by observing bacterial growth and inhibition on agarose-containing growth media and monitoring changes in response to antibiotics for MRSA. The use of gel-antibiotic modified electrode sensors to monitor inhibited and uninhibited bacterial growth is a relevant example of this approach. This technique has been used to probe the antibiotic susceptibility of MRSA and E. coli . The authors note that this method could be applied to other bacteria as well and could prove to be a valuable tool for rapid antibiotic susceptibility testing. Overall, the use of hydrogel interfaces in combination with electrochemical sensors provides a promising avenue for developing new and more effective methods for detecting and analysing bacterial growth and antibiotic susceptibility. Derrick Butler et. al , describes an interesting approaches for measuring bacterial growth and metabolism(Figure ). The technique involves the use of 3D interdigitated microelectrodes integrated with a gel-based bacterial culture. This technique relies on measuring the non-faradaic impedance of the microelectrodes and is able to differentiate between live and dead cells. The microelectrode design increases the sensing area almost three-fold and is capable of detecting 10 cells/mcL of E. coli in just one hour. However, the article notes that there are limitations to this method, and the clinical viability of this work has yet to be demonstrated. Additionally, the study only explores the differentiation between live and dead cells and does not provide data on minimum inhibitory concentrations (MIC) against antibiotics. Daniel C. Spencer et. al . introduced a novel approach to AST(Figure ), which they called "iFAST." This method is based on microfluidic impedance cytometry, a well-established label-free technique used for characterizing mammalian cells, but adapted to mimic fluorescence-activated cell sorting (FACS). iFAST measures changes in the biophysical properties of bacteria after exposure to antibiotics, allowing for rapid and sensitive AST. The technique works by measuring the electrical properties of single particles as they flow between microelectrodes in a microfluidic chip, allowing for measurement at the single-cell level. The authors suggest that the simplicity of this measurement technique makes it a promising candidate for a new generation of rapid tests in the clinical laboratory. In addition to its ability to detect antibiotic resistance, iFAST can also monitor subpopulations of bacteria that may be resistant or tolerant to antibiotics, providing realtime data on the emergence of resistance. However, the clinical feasibility of population analysis has not been demonstrated in this study. While the iFAST approach shows considerable promise, a fully-realized, miniature, and integrated rapid AST system is required to reliably predict AST for a range of pathogens and resistance mechanisms. Nonetheless, this study provides a valuable contribution to the development of improved therapies and a better understanding of complex bacterial phenotypes. The conductometric approach developed by Xuzhi Zhang et al represents a promising method for antibiotic susceptibility testing (AST) due to its noncontact nature and suitability for handling resistant and biosafety level 3 pathogens(Figure ). The authors of this study validated the conductometric culturesuspension-sensor (CCS) AST method, utilizing E. coli and V. parahaemolyticus as microorganism models and enoxacin, florfenicol, ampicillin, kanamycin, and sulfadiazine as antibiotic probes. The results indicated that the CCS AST method was clinically valid, with MICs obtained through the CCS AST assays being higher than those obtained through the standard broth microdilution (BMD) AST assays in 72% of cases. The CCS AST method offers numerous advantages, including affordability, accuracy, sensitivity, and user-friendliness, and serves as proof-of-concept for a phenotypic AST method based on the multichannel CCS. The authors suggest that this approach is superior to the BMD AST method in terms of simplicity, sensitivity, and user-friendliness. Additionally, the CCS AST method provides an automated way to perform AST assays, making it a promising high-throughput tool. The accuracy of this new method for standard bacterial strains and isolates ranges from 68.8% to 92.3%. It is expected that this approach will provide clinical laboratories with a versatile platform for rapid MIC determination of diverse types of microorganisms, including adherent species. The conductometric system utilized in the CCS AST method can also be easily reproduced in the laboratory and can even be configured in a capillary format. Yichao Yang et al. have developed a novel microfluidic device that shows promise for urinary tract infection (UTI) diagnosis(Figure ). The device monitors fluctuations in electrical resistance of E. coli in the presence and absence of antibiotics within a microfluidic channel. In order to determine its clinical validity and suitability for use, further testing is required in the form of focused parametric studies. Domingo-Roca et al. have described a portable 3D printed impedance-based biosensor that offers a promising approach for rapid antibiotic susceptibility testing. The customized electrode design allows for gel modification, enabling the detection of bacterial growth, death, and cell growth inhibition in just 90 minutes using a sample volume as low as 100uL. Electrochemical impedance spectroscopy was utilized to identify growth profiles and confirm antibiotic susceptibility of Escherichia coli and Pseudomonas aeruginosa. Antibiotic sensitivity determination was possible in just 90 minutes following overnight culture, significantly faster than the current gold standard that takes 24-48 hours. The gel-modified electrochemical sensor supports prokaryotic cell adhesion and can be used to induce cellular growth and death. This biosensor is a significant advancement in the field of antibiotic susceptibility testing, and it has the potential to improve clinical outcomes by enabling timely administration of appropriate antibiotic therapy. Giampaolo Pitruzzello et al. conducted a innovative study to demonstrate the capability of impedance spectroscopy to measure signatures of single bacteria, with the time of action of antibiotics affecting the duration of the test(Figure ). The method was also assisted by microfluidics. However, it is important to note that bacteria must be in a metabolically active state at the time of the test, which is a requirement shared by most of the techniques discussed in this review article which can be troublesome in certain scenario. Thus, impedance spectroscopy has shown great promise in the field of antimicrobial susceptibility testing, and there have been many exciting developments in this area in recent years, combining impedance spectroscopy with other techniques, such as dielectrophoresis, can further enhance its capabilities. Dielectrophoresis can be used to manipulate the movement of bacteria and other particles using electric fields (Figure ), which can help to improve the sensitivity and specificity of impedance measurements, and with a results provided within 1hrs. here are also many other potential applications of impedance spectroscopy in microbiology and biomedicine, such as for monitoring cell viability, detecting bacterial infections, and studying the effects of drugs and other compounds on cells and tissues . Also, Impedance spectroscopy enables the detection of significant parameters such as the bacteriostatic or bactericidal characteristics of novel and existing antimicrobial compounds and whole cell detection of vancomycin susceptibility .