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We report novel three-dimensional (3D) microcavity array electrodes for high-capacitance all-solid-state microsupercapactiors. The microcavity arrays are formed in a polymer substrate via a plasma-assisted reactive ion etching (RIE) process and provide extra sidewall surface areas on which the active materials are grown in the form of nanofibers. This 3D structure leads to an increase in the areal capacitance by a factor of 2.56 for a 15-μm-deep cavity etching, agreeing well with the prediction. The fabricated microsupercapactiors exhibit a maximum areal capacitance of 65.1 mF cm(-2) (a volumetric capacitance of 93.0 F cm(-3)) and an energy density of 0.011 mWh cm(-2) (a volumetric energy density of 16.4 mWh cm(-3)) which substantially surpass previously reported values for all-solid-state flexible microsupercapacitors. The devices show good electrochemical stability under extended voltammetry cycles and bending cycles. It is demonstrated that they can sustain a radio frequency (rf) microsystem in a temporary absence of a power supply. These results suggest the potential utility of our 3D microsupercapactiors as miniaturized power sources in wearable and implantable medical devices.

An ultra low power, wirelessly-powered RF transceiver for wireless sensor network is implemented using 180 nm CMOS technology. We propose a 98 μW, 457.5 MHz transmitter with output radiation power of -22 dBm. This transmitter utilizes 915 MHz wirelessly powering RF signal by frequency division using a true-single-phase-clock (TSPC) divider to generate the carrier frequency with very low power consumption and small die area. The transmitter can support up to 5 Mbps data rate. The telemetry system uses an 8-stage Cockcroft-Walton rectifier to convert RF to DC voltage for energy harvesting. The bandgap reference and linear regulators provide stable DC voltage throughout the system. The receiver recovers data from the modulated wireless powering RF signal to perform time division multiple access (TMDA) for the multiple node system. Power consumption of the TDMA receiver is less than 15 μW. Our proposed transmitter and receiver each occupies 0.0018 mm 2 and 0.0135 mm 2 of active die area, respectively.Index Terms-Energy harvest, low power wireless transceiver, time division multiple access, wireless sensor network.

To achieve the continuous surveillance capable multirotor type solar-powered unmanned aerial vehicle (UAV), we develop the photovoltaic power management system (PPMS) which manages power from photovoltaic (PV) modules and a battery pack to support the power of the UAV. To estimate the possible flight time of the UAV, we use the concept of state of charge (SOC) estimation based on the extended Kalman filter (EKF) and complementary filter (CF) and then calculate the possible flight time by using the slope of the SOC graph during hovering flight mode. According to the results, estimated flight time increases up to 54.14 min at 11:00 a.m. and decreases down to 6.70 min at 18:00 p.m.

Electrochemical biosensors are superior technologies that are used to detect or sense biologically and environmentally significant analytes in a laboratory environment, or even in the form of portable handheld or wearable electronics. Recently, imprinted and implantable biosensors are emerging as point-of-care devices, which monitor the target analytes in a continuous environment and alert the intended users to anomalies. The stability and performance of the developed biosensor depend on the nature and properties of the electrode material or the platform on which the biosensor is constructed. Therefore, the biosensor platform plays an integral role in the effectiveness of the developed biosensor. Enormous effort has been dedicated to the rational design of the electrode material and to fabrication strategies for improving the performance of developed biosensors. Every year, in the search for multifarious electrode materials, thousands of new biosensor platforms are reported. Moreover, in order to construct an effectual biosensor, the researcher should familiarize themself with the sensible strategies behind electrode fabrication. Thus, we intend to shed light on various strategies and methodologies utilized in the design and fabrication of electrochemical biosensors that facilitate sensitive and selective detection of significant analytes. Furthermore, this review highlights the advantages of various electrode materials and the correlation between immobilized biomolecules and modified surfaces.