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Traditional analytical methods are often time-consuming and require bulky instruments, making their widespread implementation challenging. This paper aims to represent the principal concepts of biosensors as an introduction of this technology to readers and offers a comprehensive understanding of its functions.

The authors provide descriptions of the components, characteristics and advantages of biosensors along with the immobilization methods, followed by a brief discussion.

A biosensor is an analytical device comprising a specific biomolecule and a transducer in conjunction with an output system. The biomolecule recognizes a specific target which leads to a change in physicochemical properties of a system. This biorecognition phenomenon is later converted into a detectable signal by the transducer. Biosensors can essentially serve as rapid and cost-effective devices with excellent sensitivity and specificity for critical purposes in innumerable fields, ranging from scientific research to day-to-day applications.

Here, the authors explain and discuss the approaches and challenges with the aim of leading to an interest in biosensor development and improving their applications.

This paper aims to provide a detailed review of weak interaction biosensors and several common biosensor methods for magnifying signals, as well as judiciously guide readers through selecting an appropriate detecting system and signal amplification method according to their research and application purpose.

This paper classifies the weak interactions between biomolecules, summarizes the common signal amplification methods used in biosensor design and compares the performance of different kinds of biosensors. It highlights a potential electrochemical signal amplification method: the G protein signaling cascade amplification system.

Developed biosensors which, based on various principles, have their own strengths and weaknesses have met the basic detection requirements for weak interaction between biomolecules: the selectivity, sensitivity and detection limit of biosensors have been consistently improving with the use of new signal amplification methods. However, most of the weak interaction biosensors stop at the research stage; there are only a minority realization of final commercial application.

This paper evaluates the status of research and application of weak interaction biosensors systematically. The G protein signaling cascade amplification system proposal offers a new avenue for the research and development of electrochemical biosensors.

The purpose of this paper is to present possibility of fast and certain identification of bovine serum albumin (BSA) by means of ion-sensitive field effect transistor (ISFET) structures. Because BSA can cause allergic reactions in humans, it is one of reasons for development of sensitive sensors to detect residual BSA. BSA is commonly used in biochemistry and molecular biology in laboratory experiments. Therefore, to better understand the mechanism of signal transduction in simulated biological environment and to elucidate the role of adsorption of biomolecules in the generation of a signal at the interface with biological systems, the measurements of ISFET current response in the presence of BSA as a reference protein molecule were performed.

To fabricate transistors, silicon technology was used. The ISFET structures were coupled to specially designed double-side printed circuit board holder. After modification of the field effect transistor (FET) device with 3-aminopropyltriethoxysilane (APTES), a sensor with high sensitivity toward reference biomolecules was obtained. The current–voltage (I-V) characteristics of structures with and without gate modification were measured. Keithley SMU 236/237/238 measurement set was used. Deionized water solution and 0.05 per cent BSA were used.

In this research, a method of preparation of a biosensor based on a FET was developed. Sensitivity of APTES-modified FET device toward BSA as a biomolecule was investigated. I-V relationships of FET devices (with and without modification), being the effect of the interactions with the solution containing 0.05 per cent BSA, were measured and compared to the measurements performed for solutions without BSA.

Compared to SiO₂-containing ISFETs without modification or other different dielectrics, the application of APTES as the part of the membrane induced significant increase in their sensitivity to BSA.

This paper aims to concentrate on research that has been conducted in the previous decade on metamaterial (MTM)-based sensors for material characterization, which includes solid dielectrics, micro fluids and biomolecules.

There has been a vast advancement in sensors based on MTM since the past few decades. MTM elements provide a sensitive response to materials while having a tiny footprint, making them an appealing alternative for realizing diverse sensing devices.

Related research papers on MTM sensors published in reputable journals were reviewed in this report, with a specific emphasis on the structure, size and nature of the materials characterized. Because electromagnetic wave interaction excites MTM structures, sensing applications around the electromagnetic spectrum are possible.

The paper contains valuable information on MTM sensor technology for material characterization, and this study also highlights the challenges and approaches that will guide future development.

The purpose of this paper was to systematically study the electrical properties of 5‐, 42‐ and 75‐nm gap polysilicon structures to evaluate the potentiality of these structures to be used in biomolecular sensing devices.

The authors previously reported the fabrication and morphological characterization of these structures. In this report, they electrically probed the presence of nanogap through current measurement. The effects of electrolytes on the capacitance profiles of these structures were systematically studied with air, water and various dilutions of phosphate buffer saline.

An increment in capacitance was found with the increment in electrolyte concentration. Improvement in current flow, capacitance, permittivity, and conductivity were observed with the smaller size nanogaps, suggesting their applications in low power consuming devices.

Since nanogap‐based dielectric biosensing devices need to be operated with a low level of current to avoid biomolecular damage, these structures should have potential applications in dielectric‐based biomolecular detection using a low cost dielectric analyser.

The purpose of this paper is to deal with utilization of marine trash fish (MTF) in the production of organic liquid fertilizer for effective solid waste management in urban locations.

Chopped MTF was treated with molasses and allowed to bacterial degradation. Spectroscopic tools – FT-IR and GC-MS were employed to characterize the biomolecules were employed to characterize the biomolecules. Nutrient content in final organic liquid fertilizer was estimated by physico-chemical analysis. The liquid fertilizer was treated to soil and applied as a foliar spray on leaves of Tomato plants and growth parameters such as height of plants (cm), number of leaves and diameter of leaves (cm) were monitored.

MTF was converted to organic liquid fertilizer using Bacillus subtilis. GC-MS analysis of the final product detected presence of fatty acids that could enrich organic carbon (OC) upon soil application. The final product possesses various organic nutrients to assist plant growth. Tomato plants treated with 5 and 10 per cent organic fertilizer showed highest height than plants treated with chemical fertilizer.

Urban solid waste management is essentially required in developing countries to reduce its impact on the environment and this approach would be helpful for effective utilization of MTF in organic agriculture.

Nanogap electrodes have important applications in power saving devices, electrochemical sensors and dielectric detections of biomolecules. The purpose of this paper is to report on the fabrication and characterization of polysilicon nanogap patterning using novelties technique.

Polysilicon material is used to fabricate the nanogap structure and gold is used for the electrode and two chrome masks are used to complete this work; the first mask for the nanogap pattern and a second mask for the electrode. The method is based on the control of the coefficients (temperature and time) with an improved pattern size resolution thermal oxidation.

Physical characterization by scanning electron microscopy (SEM) demonstrates such nanogap electrodes could be produced with high reproducibility and precision. Electrical characterization shows that nanogap enhanced the sensitivity of the device by increase the capacitance and the conductivity as well. They have also good efficiency of power consumption with high insulation properties.

With this technique, there are no principal limitations to fabricating nanostructures with different layouts down to several different nanometer dimensions. The paper documents the fabrication of nanogaps electrodes on a polysilicon, using low‐cost techniques such as vacuum deposition and conventional lithography. Polysilicon is a low‐cost materials and has desirable properties for semiconductor applications. A method of preparing a nanogap electrode according to the present innovation has an advantage of providing active surface that can easily be modified for immobilizations of biomolecules.

Nanobiosensors based on nanogap capacitor are widely used for measuring dielectric properties of DNA, protein and biomolecule. The purpose of this paper is to report on the fabrication and characterization polysilicon nanogap patterning using novelties technique.

Overall, the polysilicon nanogap pattern was fabricated based on conventional lithographic techniques. For size expansion technique, by employing simple dry thermal oxidation, the couple of nanogap pattern has been expanded to lowest nanogap value. The progress of nanogap pattern expansion was verified by using scanning electron microscopy (SEM). Conductivity, resistivity, and capacitance test were performed to characterize and to measure electrical behavior of full device fabrication.

SEM characterization emphasis on the expansion of polysilicon nanogap pattern increasing with respect to oxidation time. Electrical characterization shows that nanogap enhanced the sensitivity of the device at the value of nano ampere of current.

These simple least‐cost method does not require complicated nanolithography method of fabrication but still possible to serve as biomolecular junction. This approach can be applied extensively to different design of nanogap structure down to several nanometer levels of dimensions. A method of preparing a nanogap electrode according to the present innovation has an advantage of providing active surface that can be easily modified for immobilizations of biomolecules.

Molecular imprinting is a generic technology, which introduces recognition properties into synthetic polymers using appropriate templates. Over the last two decades molecularly imprinted polymers (MIPs) have become a focus of interest for scientists engaged in the development of biological and chemical sensors. This is due to the many and considerable advantages they possess in comparison to natural receptors, enzymes and antibodies such as superior stability, low cost and ease of preparation. This brief review covers recent achievements and potential applications of imprinted sensors with specific reference to the environment and biotechnology.

This paper aims to report an insightful portable microfluidic system for rapid and selective sensing of Hg²⁺ in the picomolar (pM) concentration using microcantilever-based piezoresistive sensor. The detection time for various laboratory-based techniques is generally 12–24 h. The majority of modules used in the proposed platform are battery oriented; therefore, they are portable and handy to carry-out on-field investigations.

In this study, the authors have incorporated the benefit of three technologies, i.e. thin-film, nanoparticles (NPs) and micro-electro-mechanical systems, to selectively capture the Hg²⁺ at the pM concentration. The morphology and topography of the proposed sensor are characterized using field emission scanning electron microscopy and verification of the experimental results using energy dispersive X-ray.

The proposed portable microfluidic system is able to perform the detection in 5 min with a limit of detection (LOD) of 0.163 ng (0.81 pM/mL) for Hg²⁺, which perfectly describes its excellent performance over other reported techniques.

A microcantilever-based technology is perfect for on-site detection, and a LOD of 0.163 ng (0.81 pM/mL) is outstanding compared to other techniques, but the fabrication of microcantilever sensor is complex.

Many researchers used NPs for heavy metal ions sensing, but the excess usage and industrialization of NPs are rapidly expanding harmful consequences on the human life and nature. Also, the LOD of the NPs-based method is limited to nanomolar concentration. The suggested microfluidic system used the benefit of thin-film and microcantilever devices to provide advancement over the NPs-based approach and it has a selective sensing in pM concentration.