Sharif Digital Repository

An impedimetric human papilloma virus (HPV) DNA biosensor based on gold nanotubes (AuNTs) in label free detection was materialized. The AuNTs decorated nanoporous polycarbonate (AuNTs-PC) template as biosensor electrode was fabricated by electrodeposition method. The single strand DNA (ss-DNA) probe was covalently immobilized onto the AuNTs-PC electrode. The hybridization of target sequences with the ss-DNA probe was observed by the electrochemical impedance spectroscopy (EIS). The biosensor showed high selectivity and could differentiate between the complementary, mismatch and non-complementary DNA sequences. The EIS measurements were matched to Randle's equivalent circuit. The... 

Humans need the five senses to understand and interact constructively with their surrounding environment; in the world of robots and intelligent systems, this is achieved using sensors. In the modern world, tactile sensors based on triboelectric effect play a prominent role in important application areas such as health monitoring, human-computer interaction, robotics, pressure mapping, and electronic signature. Triboelectric nanogenerators (TENGs) are one type of energy harvesting systems that convert mechanical energy into electrical energy. In these sensors, due to the contact and touch with the triboelectric material, an electric charge is generated and induced into the electrode, then... 

In the last half century, the recording of the electrophysiological activities of the neurons has been one of the most effective methods for neuroscience development. One of the techniques used to record the activity of the nerve cells is the use of multi-electrode arrays (MEAs). Current MEAs still face limitations such as low signal-to-noise ratio (SNR) and low spatial resolution. There is a need to develop arrays that are smaller in size and have less impedance to achieve better spatial resolution and lower noise levels. The main focus of this research is on the designing and fabrication of multi-electrode arrays and improvement of their properties using nanostructures and conductive... 

Titanium trisulfide (TiS3), a transition metal chalcogenide, bears the potential to replace silicon, when taking the form of nanoflakes, due to its favorable band gap and optical response. In this work, first we investigate the response of TiS3 nanoflakes to gas detection through a careful quantum computational approach and a few succinct measurements. The computations are benchmarked and compared with a relevant experiment at each step, where their results/conclusions are discussed. The most stable surface of TiS3 particles is determined to (001), in agreement with the literature. The adsorption of 5 gas molecules is characterized through formulating and estimating their adsorption... 

Triboelectric nanogenerator (TENG) works based on the accumulation of electrostatic charges produced on the surface of two dissimilar materials while they are brought into physical contact. When the surfaces are separated by a mechanical force, the induced triboelectric charges generate a potential drop, which can lead to generate an electrical current. Since their invention in 2012, TENGs have shown a rapid development in diversity of structure, amount of output power and range of applications, such as self-powered sensors, touch pads, and smart skin. Various kinds of mechanical force can be used for producing electrical energy: human motion, walking, vibration, rotating tire, wind, flowing... 

In the presence of spatially non-uniform electric field, a dielectric object can experience a translational force which is known as Dielectrophoresis (DEP) force. DEP is one of the most applicable methods in sorting mechanism of different biological cells. Moreover accurately measuring the DEP force in single cell level can lead to a valuable knwoledge about the electrical properties of various cells.In this thesis, first, the other electrokinetic forces in which the Electro-Osmosis (EO) force is the important one, have to be eliminated. Regarding that this effect is strongly dependent on the frequency of external E field, we have applied the external electric field at appropriate frequency...