Bioinspired hydrogels have promising prospects in applications such as wearable devices, human health monitoring equipment, and soft robots due to their multifunctional sensing properties resembling natural skin. However, the preparation of intelligent hydrogels that provide feedback on multiple electronic signals simultaneously, such as human skin receptors, when stimulated by external contact pressure remains a substantial challenge. In this study, we designed a bioinspired hydrogel with multiple conductive capabilities by incorporating carbon nanotubes into a chelate of calcium ions with polyacrylic acid and sodium alginate. The bioinspired hydrogel consolidates self-healing ability, stretchability, 3D printability, and multiple conductivities. It can be fabricated as an integrated strain sensor with simultaneous piezoresistive and piezocapacitive performances, exhibiting sensitive (gauge factor of 6.29 in resistance mode and 1.25 kPa–1 in capacitance mode) responses to subtle pressure changes in the human body, such as finger flexion, knee flexion, and respiration. Furthermore, the bioinspired strain sensor sensitively and discriminatively recognizes the signatures written on it. Hence, we expect our ideas to provide inspiration for studies exploring the use of advanced hydrogels in multifunctional skin-like smart wearable devices.

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Series impedance and shunt admittance parameters of transmission lines are fundamental data for various online and offline power system studies. This paper shows that the active power, reactive power and voltage magnitude (P, Q, V) data measured at the two ends of a transmission line are sufficient to determine the positive sequence line parameters. The phase angle information is not essential. Since the P, Q and V data are readily available from the supervisory control and data acquisition (SCADA) systems, the proposed method can be easily implemented in existing control centers. Algorithms, characteristics, performances and potential applications of the proposed method are presented in this paper. Simulation study and field test results show that the proposed technique can be a useful addition to the energy management systems (EMS) of utility companies.

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