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

Abstract

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 NO 2 − 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.

An Electroanalytical Enzymeless α-Fe2O3-ZnO Hybrid Nanostructure-Based Sensor for Sensitive Quantification of Nitrite Ions

“…Enzymeless nitrite sensing technologies leverage nanostructured materials as catalytic agents to enhance the electrochemical reaction on electrode surfaces in nitrite’s presence [ 10 , 11 , 16 , 17 , 18 ]. In this regard, an extensive effort has been made to synthesize different nanostructured materials with unique physicochemical properties of natural enzymes [ 16 , 17 , 18 ]. Such nanomaterials are known as “nanozymes”.…”

Nanometer-Sized MIL-101(Cr) Loaded with Metal Ions for Applications as a Nitrite Sensor with Enhanced Electrochemical Properties

“…The International Agency for Research on Cancer has included nitrite in the list of group 2A carcinogens, and the World Health Organization (WHO) has stipulated that the maximum content of nitrite in drinking water is 65.2 μM. − Therefore, the detection of nitrite holds significant importance in various fields. There are many methods for detecting nitrite, and electrochemical detection stands out due to its simplicity, rapidity, low cost, and high sensitivity. − …”