Advances and New Perspectives in Micro-Nanofabricated Sensors for Bioanalysis

“Micro-Nanofabricated Sensors for Bioanalysis” represents a cutting-edge field in biosensing technology which leverages the integration of micro- and nanoscale fabrication techniques [...

Integration of Ultrathin Bubble Walls and Electrochemistry: Innovation in Microsensing for Forensic Nitrite Detection and Microscale Metallic Film Deposition

We present a strategy for electrochemical measurements using a durable minute bubble wall with a thickness of 27 μm (D = 1.8 cm) as an innovative electrochemical medium. The composition, thickness, and volume of the tiny bubble film were investigated and estimated using the spectroscopic method and the Beer–Lambert law. A carbon microelectrode (D = 10 μm) was then employed as the working electrode, inserted through the bubble wall to function as the solution interface. First, the potential of this method for microelectrodeposition of metallic Ag and Pd films in a tiny bubble was investigated. Interestingly, microscopic images of the deposited film clearly demonstrated that the bubble thickness determines and confines the electrochemical deposition zone. In other words, innovative template-free microelectrodeposition was achieved. In the second phase of our work, microelectroanalysis of trace levels of nitrite ions was performed within the bubble wall and on a foam-covered hand, between the fingers directly, with a low limit of detection of 28 μM. This technique holds significance in criminal investigations, as the presence of NO2– ions on the hand indicates the potential presence of gunshot residue and aids in identifying suspects. In comparison to current methods, this approach is rapid, simple, cost-effective, and amenable to on-site applications, eliminating the need for sample treatment. Ultimately, the utilization of a bubble wall as a novel electrochemical microreactor can open new ways in microelectrochemical analysis, presenting novel opportunities and applications in the field of electrochemical sensors

Review-Towards the Two-Dimensional Hexagonal Boron Nitride (2D h-BN) Electrochemical Sensing Platforms

Electrochemical sensing performance of two-dimensional hexagonal boron nitride (2D h-BN) has traditionally been suppressed by their intrinsic electrical insulation and deficient electron transportation mechanism. However, the excellent electrocatalytic activity, high specific surface area, N- and B-active edges, structural defects, adjustable band gap through interaction with other nanomaterials, and chemical functionalization, makes 2D h-BN ideal for many sensing applications. Therefore, finding a pathway to modulate the electronic properties of 2D h-BN while the intrinsic characteristics are well preserved, will evolve a new generation of highly sensitive and selective electrochemical (bio)sensors. That is why extensive research has recently focused on the challenge to functionalize 2D h-BN by controlling the surface chemical reactions with external species, particularly metal nanoparticles. This review summarizes the most recent progress in the application of 2D h-BN nanosheets in electrochemical (bio)sensing. We will explore the fabrication techniques of 2D h-BN for electrochemical applications followed by thorough discussion on their advantages, shortcomings, and promising possibilities as (bio)sensing platforms in near future.Funding Agencies|Sharif Universityof Technology [QA970816]; Iran National Science Foundation (INSF)Iran National Science Foundation (INSF) [95-S-48740]; Science Foundation IrelandScience Foundation Ireland [18/SIRG/5621]</p

Colorimetric Disposable Paper Coated with ZnO@ZnS Core-Shell Nanoparticles for Detection of Copper Ions in Aqueous Solutions

In this study, we have proposed a new nanoparticle-containing test paper sensor that could be used as an inexpensive, easy-to-use, portable, and highly selective sensor to detect Cu2+ ions in aqueous solutions. This disposable paper sensor is based on ZnO@ZnS core-shell nanoparticles. The core-shell nanoparticles were synthesized using a chemical method and then they were used for coating the paper. The synthesis of the ZnO@ZnS core-shell nanoparticles was performed at a temperature as low as 60 degrees C, and so far this is the lowest temperature for the synthesis of such core-shell nanoparticles. The sensitivity of the paper sensor was investigated for different Cu2+ ion concentrations in aqueous solutions and the results show a direct linear relation between the Cu2+ ions concentration and the color intensity of the paper sensor with a visual detection limit as low as 15 mu M (similar to 0.96 ppm). Testing the present paper sensor on real river turbulent water shows a maximum 5% relative error for determining the Cu2+ ions concentration, which confirms that the presented paper sensor can successfully be used efficiently for detection in complex solutions with high selectivity. Photographs of the paper sensor taken using a regular digital camera were transferred to a computer and analyzed by ImageJ Photoshop software. This finding demonstrates the potential of the present disposable paper sensor for the development of a portable, accurate, and selective heavy metal detection technology.Funding Agencies|Shahid Chamran University; Linkoping University</p

Nanomaterial-Modified Conducting Paper : Fabrication, Properties, and Emerging Biomedical Applications

The emerging demand for wearable, lightweight portable devices has led to the development of new materials for flexible electronics using non-rigid substrates. In this context, nanomaterial-modified conducting paper (CP) represents a new concept that utilizes paper as a functional part in various devices. Paper has drawn significant interest among the research community because it is ubiquitous, cheap, and environmentally friendly. This review provides information on the basic characteristics of paper and its functionalization with nanomaterials, methodology for device fabrication, and their various applications. It also highlights some of the exciting applications of CP in point-of-care diagnostics for biomedical applications. Furthermore, recent challenges and opportunities in paper-based devices are summarized.Funding Agencies|Department of Science and Technology, New Delhi, IndiaDepartment of Science &amp; Technology (India) [DST/INSPIRE/04/2017/002750, DST/INSPIRE/04/2015/000932]; Science &amp; Engineering Research Board (Govt. of India) [SB/S9/YSCP/SERB-DF/2018]</p

Review-Textile Based Chemical and Physical Sensors for Healthcare Monitoring

The emergence of textile-based wearable sensors as light-weight portable devices to monitor desired parameters, has recently gained much interest and has led to the development of flexible electronics on non-rigid substrates. The flexible biosensors may result in improved sports performance, to monitor the desired bodies for injuries, improved clinical diagnostics and monitor biological molecules and ions in biological fluids such as saliva, sweat. In addition, they could help users with different types of disorders such as blindness. In this context, new composite and nanomaterials have been found to be promising candidates to obtain improved performance of the textile based wearable devices and to optimize the structures for intimate contact with the skin for better functionality. This review aims to provide the most recent cutting-edge information on emergence, fabrication, materials, and applications of chemical and physical flexible and stretchable textile-based (bio)sensors. Besides this, we discusss the recent key innovations and applications of textile-based sensors in healthcare.Funding Agencies|Sharif University of Technology [QA970816]; Iran National Science Foundation (INSF)Iran National Science Foundation (INSF) [95-S-48740]; Department of Science and Technology, New Delhi, IndiaDepartment of Science &amp; Technology (India) [DST/INSPIRE/04/2017/002750, DST/INSPIRE/04/2015/000932]; Science &amp; Engineering Research Board (Govt. of India) [SB/DF/011/2019]</p