Development of haptic based piezoresistive artificial fingertip: toward efficient tactile sensing systems for humanoids

Haptic sensors are essential devices that facilitate human-like sensing systems such as implantable medical devices and humanoid robots. The availability of conducting thin films with haptic properties could lead to the development of tactile sensing systems that stretch reversibly, sense pressure (not just touch), and integrate with collapsible. In this study, a nanocomposite based hemispherical artificial fingertip fabricated to enhance the tactile sensing systems of humanoid robots. To validate the hypothesis, proposed method was used in the robot-like finger system to classify the ripe and unripe tomato by recording the metabolic growth of the tomato as a function of resistivity change during a controlled indention force. Prior to fabrication, a finite element modeling (FEM) was investigated for tomato to obtain the stress distribution and failure point of tomato by applying different external loads. Then, the extracted computational analysis information was utilized to design and fabricate nanocomposite based artificial fingertip to examine the maturity analysis of tomato. The obtained results demonstrate that the fabricated conformable and scalable artificial fingertip shows different electrical property for ripe and unripe tomato. The artificial fingertip is compatible with the development of brain-like systems for artificial skin by obtaining periodic response during an applied load

A molecular neuromorphic network device consisting of single-walled carbon nanotubes complexed with polyoxometalate

In contrast to AI hardware, neuromorphic hardware is based on neuroscience, wherein constructing both spiking neurons and their dense and complex networks is essential to obtain intelligent abilities. However, the integration density of present neuromorphic devices is much less than that of human brains. In this report, we present molecular neuromorphic devices, composed of a dynamic and extremely dense network of single-walled carbon nanotubes (SWNTs) complexed with polyoxometalate (POM). We show experimentally that the SWNT/POM network generates spontaneous spikes and noise. We propose electron-cascading models of the network consisting of heterogeneous molecular junctions that yields results in good agreement with the experimental results. Rudimentary learning ability of the network is illustrated by introducing reservoir computing, which utilises spiking dynamics and a certain degree of network complexity. These results indicate the possibility that complex functional networks can be constructed using molecular devices, and contribute to the development of neuromorphic devices

Fabrication of piezoresistive based pressure sensor via purified and functionalized CNTs/PDMS nanocomposite: toward development of haptic sensors \

In this work, we reported a chemically modified technique via screen printing method to fabricate carbon nanotubes (CNTs)/Polydimethylsiloxane (PDMS) nanocomposite to monitor the piezoresistive behavior of nanocomposite while applying pressure. Raman, UV/vis and HRTEM results were utilized to verify the quality of CNTs, purified through chemical and physical treatments; carboxylic and hydroxylic functional groups were determined via FTIR. The optimum dispersion ratio of the nanocomposite was observed by FESEM images which clearly show the consistent dispersion of CNTs coated by PDMS. Furthermore, I–V characterization of the developed nanocomposite indicates change in resistivity for a few orders of magnitude before and after treatment in addition to resistance variation as a result of different applied pressures. These results indicate the importance of CNTs treatment prior to nanocomposite fabrication in order to obtain lower percolation threshold. Obtained results are useful in development of haptic sensor, artificial finger, and brain like devices for robotics applications

Vectorial crystal growth of oriented vertically aligned carbon nanotubes using statistical analysis

In this present work, crystalline growth conditions of oriented carbon nanotubes based on chemical vapor deposition (CVD) were optimized. The crystallinity and degree of alignment of the grown carbon nanotubes (CNTs) were characterized by field emission scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The effects of four variables, namely, deposition time, deposition temperature, annealing process, and concentration of the precursor on the crystallinity of the CNTs, were explored. Furthermore, the correlation of parameters with the growth mechanism was examined using response surface methodology in an attempt to determine the complex interactions between the variables. A total of 30 runs, including predicting and consolidation runs to confirm the results, were required for screening the effect of the parameters on the growth of the CNTs. On the basis of the investigated model, it was found that the crystallinity of the CNTs grown by the CVD method can be controlled via restriction of the effective parameters. (Graph Presented)

Simulation of nano sensor based on carbon nanostructures in order to form multifunctional delivery platforms

Carbon nanostructures demonstrate a perfect combination of mechanical, electrical and electro chemical properties.Different approaches can improve the selectivity and sensitivity of CNT-modified electrode through immobilization of enzymes. In this research, simulation of SWCNTs attached sensor for medical application was described.Glucose oxidase was immobilized on the surface of the CNT using microencapsulation technique with non covalent bindings which has a negligible effect on the native biological activities of the enzymes. The main advantage of the Micro-encapsulation is that the entrapped particles often maintain its nature bioactivity. ABAQUS and ANSYS are the software's which used to certify the results of experiments. Boundary conditions were selectivity detected according to the redox reaction center of enzyme and electrode surface. The results of the simulation indicate the ability of CNT to penetrate into the cells which offers the potential of using CNT as vehicles for the delivery system. Furthermore, encapsulated CNT attached sensor can work as a stress sensor simultaneously. Simulation was focused on measuring physical properties of CNTs, such as Mass, velocity, capacity and stress before and after immobilizing of GOx

Highly oriented vertically aligned carbon nanotubes via chemical vapour deposition for key potential application in CNT ropes

The remarkable properties of highly oriented vertically aligned carbon nanotubes (CNTs) make them attractive for electrical applications, especially for CNT ropes. In this paper, we describe the process to grow long oriented CNT arrays to improve the electrical properties of the devices based on CNTs. Chemical vapour deposition was used to deposit highly oriented CNTs using camphor oil as a carbon source and argon and hydrogen gas as carrier gases to grow perpendicular CNTs on the surface of the silicon substrate in presence of ferrocene as a metallic catalyst. Images obtained by field emission SEM indicate the formation mechanism of oriented CNTs with high morphological purity of nanotubes, which depends significantly on the deposition time and applied temperature to the furnaces. The TEM images confirm synthesis of multiwall CNTs (MWCNTs). This method might be an effective method of producing highly oriented MWCNTs in different aspect ratio

Constant glucose biosensor based on vertically aligned carbon nanotube composites

In this contribution, a reagent free glucose biosensor was prepared based on multi walled carbon nanotubes (MWCNTs) composite via the electrochemical method. The synthesized MWCNTs were in turn successfully optimized by the chemical vapor deposition (CVD) method. The glucose oxidase (GOx) was immobilized on a carbon nanotubes/gelatin (Gl) composite using the entrapment technique, with an 8.42 s - 1 direct electron transfer rate between GOx and MWCNTs/Gl, which was then drop - casted onto a glassy carbon electrode (GCE). The bioactivity of GOx on modified GCE was retained during the electrochemical reactions. The cyclic voltammetric results coupled with the chronoamperometric response and obtained from modified GCE indicated that a GOx/MWCNTs/Gl/GC electrode can be utilized as a glucose biosensor via its display of high sensitivity and stability. The biosensor exhibited a wide linearity range to 8.9 mM glucose, with the detection limit of 0.54 mM and a stability of 75.4% current diminish after 25 days. The proposed fabrication method of glucose biosensor was in line with the developments of electrochemical research for glucose determination of human serum in the context of electrochemical reactions. The results indicated that the biosensor possessed good stability and acceptable fabrication reproducibility

Constant glucose biosensor based on vertically aligned carbon nanotube composites

In this contribution, a reagent free glucose biosensor was prepared based on multi walled carbon nanotubes (MWCNTs) composite via the electrochemical method. The synthesized MWCNTs were in turn successfully optimized by the chemical vapor deposition (CVD) method. The glucose oxidase (GOx) was immobilized on a carbon nanotubes/gelatin (Gl) composite using the entrapment technique, with an 8.42 s - 1 direct electron transfer rate between GOx and MWCNTs/Gl, which was then drop - casted onto a glassy carbon electrode (GCE). The bioactivity of GOx on modified GCE was retained during the electrochemical reactions. The cyclic voltammetric results coupled with the chronoamperometric response and obtained from modified GCE indicated that a GOx/MWCNTs/Gl/GC electrode can be utilized as a glucose biosensor via its display of high sensitivity and stability. The biosensor exhibited a wide linearity range to 8.9 mM glucose, with the detection limit of 0.54 mM and a stability of 75.4% current diminish after 25 days. The proposed fabrication method of glucose biosensor was in line with the developments of electrochemical research for glucose determination of human serum in the context of electrochemical reactions. The results indicated that the biosensor possessed good stability and acceptable fabrication reproducibility

Fast synthesis of multilayer carbon nanotubes from camphor oil as an energy storage material

Among the wide range of renewable energy sources, the ever-increasing demand for electricity storage represents an emerging challenge. Utilizing carbon nanotubes (CNTs) for energy storage is closely being scrutinized due to the promising performance on top of their extraordinary features. In this work, well-aligned multilayer carbon nanotubes were successfully synthesized on a porous silicon (PSi) substrate in a fast process using renewable natural essential oil via chemical vapor deposition (CVD). Considering the influx of vaporized multilayer vertical carbon nanotubes (MVCNTs) to the PSi, the diameter distribution increased as the flow rate decreased in the reactor. Raman spectroscopy results indicated that the crystalline quality of the carbon nanotubes structure exhibits no major variation despite changes in the flow rate. Fourier transform infrared (FT-IR) spectra confirmed the hexagonal structure of the carbon nanotubes because of the presence of a peak corresponding to the carbon double bond. Field emission scanning electron microscopy (FESEM) images showed multilayer nanotubes, each with different diameters with long and straight multiwall tubes. Moreover, the temperature programmed desorption (TPD) method has been used to analyze the hydrogen storage properties of MVCNTs, which indicates that hydrogen adsorption sites exist on the synthesized multilayer CNTs