In this work, the authors reported the hybrid architecture of carbon nanotube (CNT)–zinc oxide (ZnO) nanowire as a multi‐functional probe in amperometric immunosensor for the detection of urine albumin. Low‐cost substrate such as glass is possible because of novel low‐temperature growth process of CNT/ZnO nanowires as a multi‐function electrode in this sensor. Based on Schottky like behaviour this structure exhibit excellent high current density to achieve higher performance. Measurement of urine albumin is a new way for early detection of diabetic and also low concentration of it in culture media is also considered in order to verify the conversion of stem cells to liver cells. Human albumin serum antibody is used as a selective and sensitive part. The amperometric performance of immunosensor is studied and showed excellent performance for detection of albumin in urine samples. Very high linear range (from 3.3 ng/µl to 3.3 mg/µl) with a correlation coefficient of 0.825 and low detection limit (3.3 ng/µl or 4.96 × 10 ⁻⁸ mol l ⁻¹ ) are the main characteristics of this sensor. Due to the high dynamic range and sensitivity, this sensor was also used in medical diagnosis and biomedical applications.

In this paper the electric field simulation of carbon nanotubes triode field emission devices is investigated. The geometry of CNTs and their arrangement on the substrate affect the screening effect and filed enhancement factor (β). In an array of nanotubes, for a distance smaller than the CNT length the screening effect is observed. The emission current density is related to the gate aperture and CNT shape. In a triode structure the screening effect occurs in the intertube distances about half of the CNT’s length due to the presence of the gate plate. Furthermore, the presence of the metal-oxide gate has a favorable effect to minimize the screening effect and allows one to increase the density of CNT’s in each array spot and to increase the cluster array density on the substrate, hence to increase the density of emission current and emitter sites where a high current density is required.

In this study, a new method is presented to fabricate spiral shape single fiber. The micro-needle array (40 μm hole diameter, 80 μm outer diameter, and 100 μm height) is utilized instead of the needle to reduce the diameter of fibers which are electrospun from 23Wt% PVP concentration. In order to have fine and bead-free fibers, the structural parameters of the micro-needle array and space which close microneedles act as an individual one are simulated. The Wet and Dry Etching techniques are used for fabrication of micro-needles. The experimental setup consists of the stepper motor and micrometer head as the pump, distance controller, and voltage generator. The single fiber can be electrospun by applying 1–3 kV bias within 1 mm gap between micro-needle and collector. Using nonconductive collector causes the formation of spiral type single fiber instead of agglomerate fiber. Elastic and expulsion forces in charged fibers seem to be the main reasons of fiber separation and spiral shape formation. The spiral shape fiber is made without traditional lithography techniques like direct patterning or contact exposure which are more expensive and time-consuming. The alteration in the fiber pattern can be seen by changing the applied voltage and spinneret, microneedle and needle. After various experiments, spirality pattern electrospun by microneedle with 10–15 μm and 15–35 μm distribution area of first and second circles and 500–570 nm and 570–660 nm diameter of first and second circles is gained as the structure with minimum distribution area and fiber width. This structure is created when the applied voltage and distance between microneedle and collector are 1kV and 1 mm.