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In the current scenario, COVID-19 has created a havoc negative impact on the lives of the people, which have triggered the research interest on the design and development of sensitive, low cost and power-efficient sensors for detecting a wide variety of biomolecules. Here, a novel hetero dielectric (HD) hetero material (HM) Bio-RFET based sensor is proposed which works as n or p MOSFET and n or p TFET and hence, is capable to sense the biomolecules through label-free dielectric modulation technique. Without labelling expenses, this biosensor detects a number of biomolecules present in human body as and when kept in a nano cavity. The dielectric polarization within the nanocavity due to the presence of foreign biomolecules under the influence of an electric field causes a variation in drain current. In this paper (SiO2 + TiO2) and AlGaAs/Si based HD-HM-RFET is explored for biosensing applications and mole fraction optimization of AlGaAs is done to obtain better results for four FETs. Work function of 4.5 eV is used in over drain and source electrodes, while metal work function of 4.7 eV is used for gate electrode. Finally, we found that the proposed device possesses better sensing capability for varying dielectric constant (K = 20 to 80) and charge (−5 × 1011 to 1 × 1013 C/cm2) as compared to a (SiO2 + HfO2)-HM-RFET and Si based (SiO2 + TiO2)-RFET. Further, it is observed that n-(SiO2 + TiO2)-HM-TFET is the best among all FETs and has highest Id-Vgs sensitivity = 5.09 × 1013, ION/IOFF = 1.23 × 109, lowest SS = 20.3 mV/dec and Vth = 1.48 V.

Silica nanoparticles (SNPs) have shown great applicability potential in a number of fields like chemical, biomedical, biotechnology, agriculture, environmental remediation and even wastewater purification. With remarkably instinctive properties like mesoporous structure, high surface area, tunable pore size/diameter, biocompatibility, modifiability and polymeric hybridizability, the SNPs are growing in their applicable potential even further. These particles are shown to be non-toxic in nature, hence safe to be used in biomedical research. Moreover, the molecular mobilizability onto the internal and external surface of the particles makes them excellent carriers for biotic and non-biotic compounds. In this respect, the present study comprehensively reviews the most important and recent applications of SNPs in a number of fields along with synthetic approaches. Moreover, despite versatile contributions, the applicable potential of SNPs is still a tip of the iceberg waiting to be exploited more, hence, the last section of the review presents the future prospects containing only few of the many gaps/research extensions regarding SNPs that need to be addressed in future work.

In this paper, we present a double gate JL-TFET based biosensor by varying the gate dielectric constant to detect various biomolecules through label-free detection technique. An investigation regarding properties and behavior device has been investigated with the help of Silvaco TCAD. It is observed that Junction less TFET has advantageous over JLFET and TFETdue to the absence of junctions. The proposed device shows reduced short channel effects, lower subthreshold swing along with a higher voltage gain. The detection of the biomolecule is done by varying the gate dielectric constant inside the cavity and different electrical parameters such as electric field, sensing current, threshold voltage and transconductance are observed. The change in the threshold voltage, drain current, transconductance has been used as the sensing metric to detect the sensitivity of the presented device for biomolecule detection. Biomolecule position inside the cavity have been investigated to find out their effect on sensitivity parameter.

Commercial polyethylene (PE) fiber-based masks are currently used as personal filters for protection against various microorganisms. Due to the coronavirus (SARS-CoV-2) pandemic of 2020, the use of masks has become the critical mechanism in reducing the spread. The PE mask filter uses a sieve (geometry) in a spider web fashion to filter out microorganisms using Van der Waals atomic forces. However, the non-geometrical part of the filtration process is not fully understood. In this work, we utilized luminescent ultra-small silicon nanoparticles, which are Si-H or/and Si-OH terminated to examine how the filter operates at a chemical level. The particles were sprayed onto the fiber network by an atomizer and we used scanning electron microscopy (SEM), optical microscope and fluorescence spectroscopy under UV radiation. The images and measurements clearly showed that the Si nanoparticles bonded to the PE fiber network. The results were analyzed in terms of chemical bonding between Si nanoparticle and fiber. Our findings suggest that the PE fibers could act as a chemical filter via hydrogen or hydrolysis-based bonding or via Si-C bonding, which is complementary to their physical filtration ability via the geometric sieve process. Graphic Abstract

TFET based label-free biosensors are fast, sensitive and more power efficient as compared to CMOS biosensors, which are prone to short channel effects (SCEs). However, literature is flooded with various TFET biosensors that have become the reason of dilemma for researchers during pandemic situations like COVID-19. Therefore, in this work, a physically doped (PD), charge plasma (CP) and electrically doped (ED) dielectric modulated (DM) TFET based label-free biosensors are compared, which cover almost the entire range of doping and junctionless devices. Also, we found that the ED based TFET biosensors provide better current sensitivities of 5.10 x 10(7), 4.77 x 10(8) and 7.11 x 10(8) for biomolecules with K=12, positive charge= 1 x 10(13) C/cm(2) and negative charge= -1 x 10(13) C/cm(2) respectively. Hence, ED-DM-TFET based biosensors can act as promising candidates to provide better detection and identification quality.

The most affected disease in recent years is Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-COV-2) that is notable as COVID-19. It has been started as a disease in one place and arisen as a pandemic throughout the world. A serious health problem is developed in the lungs due to the effect of this coronavirus. Sometimes it may result in death as a consequence of extensive alveolar damage and progressive respiratory failure. Hence, early detection and appropriate diagnosis of corona virus in patient’s body is very essential to save the lives of affected patients This work evolves a Silicon (Si) based label-free electrical device i.e. the reduced graphene oxide field-effect transistor (rGO FET) for SARS-CoV-2 detection. Firstly rGO FET functionalized with SARS-CoV-2 monoclonal antibodies (mAbs). Then the rGO FET characteristic response is observed to detect the antibody-antigen reaction of SARS-CoV-2 with different molar ranges. The developed GFET shows better performance towards the drain current and limit-of-detection (LoD) up to 2E-18 M. Therefore, we believe that an intense response was observed than the earlier developed devices and signifies impressive capability for subsequent implementation in point-of-care (PoC) diagnostic tests.

In the current study, by employing first-principles computations, the adsorption behavior of letrozole (LET) was investigated on the pristine graphdiyne nanosheet (GDY) as well as Si-doped graphdiyne (SiGDY). According to the adsorption energy, charge transfer value, and the change in the bang gap energy, the tendency of the pristine GDY towards LET is insignificant. However, the interaction of LET with SiGDY was strong and the adsorption energy was approximately − 19.20 kcal/mol. In addition, the associated electrical conductivity with SiGDY increased by approximately 23.53 % following the adsorption of LET. The results show that SiGDY can be employed as an electronic sensor to detect LET. Furthermore, LET is detected by SiGDY in the water phase based on the magnitude of solvation energy. Finally, a considerable charge-transfer between LET and SiGDY is a precondition for the adsorption of the LET molecule with proper binding energies, which delivers the Si atoms with a significant positive charge.