摘要: When stimulated, each electrocyte of the electric eel can generate 150 mV via ion transportation through highly selective ion channels on cell membranes. ### Printable power inspired by eels Printed energy storage devices can provide power to wearable devices. Lu Yang et al. used electric eels, which rely on sodium and potassium ion gradients to generate currents, for inspiration in developing alternatives to hazardous components in batteries. The authors developed two inks from graphene oxide, a permeable material with enhanced conductivity of positively charged ions. The two inks differed in their concentrations of potassium cations. Silver electrodes were also printed onto the paper. When moisture was introduced, reduction and oxidation of the silver produced a current, and potassium ions moved within the 2D nanofluidics in the graphene oxide, generating 1.2 volts per cell. The silver electrodes also served to transform the ion migration into an electric current. When the authors printed 175 of these cells in a series, they generated 192 volts of electricity. In the absence of moisture, such as in a vacuum bag, the voltage was zero. Using this approach, the authors created a 3D cell. According to the authors, the performance of the power source is similar to lithium thin-film batteries and could aid the development of wearable electronics. — T.H.D. Read online ### Geometric intuitions are present in humans but not baboons Humans are unique among primates in their ability to create formal symbolic systems that capture regularities in the external world. Mathias Sablé-Meyer et al. provide evidence that humans, but not baboons, use a symbolic strategy to process the regularities of geometric shapes, regardless of age, culture, or education. The authors generated 11 quadrilaterals, or four-sided shapes, that varied in their number of geometric regularities, including parallel lines, equal angles, equal sides, and right angles. During each trial, 605 adults were asked to identify a deviant among six shapes presented. Both …