Here, we propose the fabrication of a solid state fractional capacitor for which constant phase (CP) angles were attained in different frequency zones: 110 Hz–1.1 kHz, 10 kHz–118 kHz, and 230 kHz–20 MHz. The configuration makes use of epoxy resin as the matrix in which multi-walled carbon nanotubes (MWCNTs) are dispersed. Adhesive nature of the epoxy resin is utilized for binding the electrodes, which avoids the extra step for packaging. The fractional capacitive behavior is contributed by the distribution of time constants for the electron to travel from one electrode to the other. The distributive nature of the time constant is ensured by inserting a middle plate which is coated with a porous film of polymethyl-methacrylate in between the two electrodes. The phase angle trend for the configuration is studied in detail, and it is observed that as the % of carbon nanotubes (CNTs) loading increases, the CP angle increases from $-85°$ to $-45°$ in the frequency zones above 100 Hz. The developed device is compact and it can be easily integrated with the electronic circuits.

This paper presents a flexible and disposable humidity sensor based on Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The sensing layer is developed by drop casting PEDOT:PSS on screen printed graphene-carbon (G-C) ink based interdigitated electrodes (IDEs) on paper substrate. The humidity sensing properties are investigated in a wide humidity range (25%RH - 90%RH) at room temperature (RT; 27 °C ± 2 °C). The sensor exhibits substantial % response (118.5% at 90%RH) in the considered range with response/recovery time as 70/30 seconds (sec). The applicability of the sensor has been demonstrated for skin moisture/humidity monitoring under normal and moist conditions. A read-out circuit is designed for demonstrating the real-time monitoring of skin moisture level. The obtained results indicate the suitability of the developed sensor for skin moisture monitoring, environmental humidity monitoring, and non-contact switching is areas such as healthcare and agriculture.

Highly sensitive pressure sensors with features such as biocompatibility, biodegradability, and flexibility are needed in applications such as robotics, prosthesis, medical implants, and wearable electronics. However, due to material limitations or technological bottlenecks it is often challenging to fabricate pressure sensors with these attributes at the same time. Herein, we present biodegradable silk/PEO/yeast nanofibers based soft capacitive pressure sensor array (2 × 2). The electrospun nanofibers used here have about 150% enhanced crystallinity, as confirmed by X-ray diffraction (XRD) and Fourier Transform- Infrared spectroscopy (FT-IR). The performance metrics of the sensor array, such as sensitivity (∼0.18 kPa ^-1 ), hysteresis (<16%), minimum response (∼0.8 s), and recovery time (∼1 sec) show its suitability for application such as smart plasters used for accelerated wound healing. Further, the degradability studies confirm the quick degradation of sensors, which can also be potentially controlled with suitable packaging.

In this paper, the performance of an analog PI ${}^{\lambda }$ D ${}^{\mu }$ controller is done for speed regulation of a DC motor. The circuits for the fractional integrator and differentiator of PI ${}^{\lambda }$ D ${}^{\mu }$ controller are designed by optimal pole-zero interlacing algorithm. The performance of the controller is compared with another PI ${}^{\lambda }$ D ${}^{\mu }$ controller—in which the fractional integrator circuit employs a solid-state fractional capacitor. It can be verified from the results that using PI ${}^{\lambda }$ D ${}^{\mu }$ controllers, the speed response of the DC motor has improved with reduction in settling time ( $T_s$ ), steady state error (SS error) and % overshoot (% $M_p$ ).