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Wireless, passive, and cost-efficient monitoring of moisture within packaged food and medicine is important to ensure their safety and freshness. This paper presents paper-based single spiral inductance–capacitance (LC) sensors and a distance-insensitive readout system. The parasitic capacitance of the single-spiral coil is used to form an LC resonant circuit with its inductance. The printing paper is utilized as a humidity sensing material. A model for the LC sensor is analyzed and compared with HFSS simulation, showing the relative error within 6.3%. Nano-silver paste for the single-spiral coil was screen printed on the printing paper. The LC sensors with 4, 6, and 8-turns coils were characterized at relative humidity levels of 15%-90%RH by a readout coil at a fixed position. Comparison shows that the 8-turn sensor has the best linearity with respect to humidity. The sensitivity and response time were measured to be 120 kHz/%RH and 60 minutes, respectively, with the hysteresis errors less than 0.9%. During the practical monitoring, the tested signal frequency will have a shift if the coil’s relative position alters. To weaken the influence of the coil’s position, a readout coil, working at the quasi-resonant with the LC sensor was utilized to enhance the readout, resulting in more stable signal. According to the experimental results, the improved readout system can restrain the frequency shift within 1.1% at a readout distance from 2–50 mm when the ambient humidity is 60%RH. [ABSTRACT FROM AUTHOR]

Beeswax, a natural nontoxic biological material, is used as the gate dielectric of flexible low-voltage indium–zinc-oxide (IZO)-based homojunction thin-film transistors (TFTs) on paper substrates. A high specific capacitance of 5 \mu \textF /cm2 is measured at 1 Hz in the beeswax film due to the electric-double-layer effect. The current ON/OFF ratio, subthreshold swing, and field-effect mobility of the IZO-based TFTs on paper substrate are estimated to be 7.6\times 10 ^6 , 86 mV/decade, and 14.6 cm2 /Vs, respectively. In addition, our results demonstrate that the flexible oxide-based TFTs on paper substrate show a good stability after 3000 times bending and 30 days aging testing. Such flexible low-voltage oxide-based homojunction TFTs have potential applications in portable paper electronics. [ABSTRACT FROM PUBLISHER]

Low-voltage flexible dual-gate indium–tin–oxide-based thin-film transistors (TFTs) are self-assembled on \SiO2-covered paper substrates by one shadow mask diffraction method. Solution-processed chitosan gate dielectric films have a large gate specific capacitance (5.8 \mu\F/cm^2) due to the electric-double-layer effect. The subthreshold swing, drain-current on/off ratio, and field-effect mobility are estimated to be 80 mV/dec, \4 \times \10^6, and 9.3 \cm^2/\V\cdot\s, respectively. Low-voltage operation mechanism and threshold voltage modulation of such dual-gate paper TFTs are investigated. [ABSTRACT FROM AUTHOR]

This study compares cross-linked polyethylene (XLPE) cables with oil-filled cables during light load conditions and when the shunt reactors are brought into service to alleviate the problem of the high capacitance of cables. Power cables are generally single cored (i.e., single phase) at higher voltages of 275 kV and 400 kV. At 132 kV and below they may be either single cored or have three cores, one per phase. Multicore cables are generally taken to be small cross-section cables with varying standard numbers of separately insulated cores for low voltage control, protection use, etc. Like power cables, the cores lie side by side. High-voltage cables are generally insulated with many layers of special paper impregnated with oil and have free oil under pressure which is contained in a sheath. They are called "oil-filled" cables. Modem technology uses gases and plastics as insulators. Cables using XLPE have been coming into use. The capacitance of single-conductor and individually screened three-conductor cables is readily calculated. For three-conductor unscreened cables one must resort to empirical design data. Owing to the high capacitance of cables, the charging current-especially at high voltages-is an essential factor in deciding the permissible length to be used. [ABSTRACT FROM PUBLISHER]