Sharif Digital Repository

Detection and determination of ultra-trace electroactive materials using electrochemical methods have been widely employed by researchers since they offer a fast, easy and reliable approach. In this way, developing of new nanoelectrodes with special and unique properties plays a profound role on the achievement of better results.
Gold nanoelectrode ensembles are one of the most important nanoelectrodes which due to the high surface area, chemical, electrochemical and physical stability, and integration of a large number of individual nanoelectrodes, introduce excellent opportunities to be employed as promising nanoelectrodes in determinations applications.
In this work, preparation... 

Hydrogen sulfide, H2S, is a toxic gas and has detrimental effects on human health and the oil and gas industry. Therefore, its identification is very important. According to the devastating effects of this gas, then, the general mechanisms have been studied for gas detection. In addition, by highlighting the benefits of the multilayer nanostructure electrochemical sensors, an applicable and efficient method for the industrial production of these sensors has been investigated. In this regard, the sol-gel method is used to prepare the SnO2-CuO multilayer thin film and the advantages of this method was compared to PVD method. Also sensor properties of both deposition methods have been... 

In this thesis, physical properties and gas sensing application of three-dimensional graphene-based structures are studied. The three-dimensional structures of reduced graphene oxide and relative hybrids were synthesized through reducing graphene oxide aqueous solution. The arrangement of two-dimensional graphene layers in three-dimensional architectures has some advantages such as high surface area, hence increasing available adsorption sites. These properties result in changing electrical parameters of the structure, such as electrical impedance and phase angle in the presence of different mediums and alteration of temperature and pressure. Various characterization techniques like atomic... 

The aim of the current research is to study the process of making a solidstate nanopore by molding from PDMS polymer and to make a laboratory sample of a solidstate nanopore manufacturing device using this method. Solid-state nanopores are used to control ion transport in microfluidic channels,lab-on-a-chip detection to study nucleic acids and proteins, desalination, nanofluidic transistors,single-cell sensing tools, and particle classification. In general, the smaller the nanopore, the shorter the length and the higher the mechanical stability, the better the performance. In this research, chips have been made on which there is a blade with a sharpness of 10 nanometers and a height of 10... 

Detecting small particles is one of the needs of researchers. Industrial and research developments in nano and biotechnology expands the need of suitable equipments. One of the challenges in this field is detecting the qualitative and quantitative properties in the sample. Until today there are numerous methods to detect the properties of the particles and different commercial machines are presented for this purpose. In this method, based on one the methods of detecting particles, called resistive pulse sensing, a mechanism is composed and by its help 7 um and 800 to 2000 nm particles are distinguished separately. This sensor has two important parts: the fluid and the electronic. In the...