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An electromagnet is a particular device that takes advantage of electrical currents to produce concentrated magnetic fields. The most well‐known example is a conventional solenoid, having the form of an elongated coil and creating a strong magnetic field through its center when it is connected to a current source. Spontaneous redox reactions located at opposite ends of an anisotropic Janus swimmer can effectively mimic a standard power source, due to their ability to wirelessly generate a local electric current. Herein, we propose the coupling of thermodynamically spontaneous redox reactions occurring at the extremities of a hybrid Mg/Pt Janus swimmer with a solenoidal geometry to generate significant magnetic fields. These chemically driven electromagnets spontaneously transform the redox‐induced electric current into a magnetic field with a strength in the range of μT upon contact with an acidic medium. Such on‐board magnetization allows them to perform compass‐like rotational motion and magnetotactic displacement in the presence of external magnetic field gradients, without the need of using ferromagnetic materials for the swimmer design. The torque force experienced by the swimmer is proportional to the internal redox current, and by varying the composition of the solution, it is possible to fine‐tune its angular velocity. [ABSTRACT FROM AUTHOR]

Organic mixed ionic‐electronic conductors (OMIEC) have emerged as pivotal materials in organic bioelectronics, particularly when integrated into organic electrochemical transistors (OECTs). Conducting polymer‐based devices have indeed demonstrated their capability to transduce biological signals into amplified output signals, harnessing the high transconductance of OECTs. The OECT operating principle and sensing capability strongly depend on ion‐conjugated backbone coupling: the dual nature of OMIECs, i.e. ion‐conductor and electron/hole‐conductor, presents an intrinsic interface in the bulk of the thin film across which transduction of ionic signals into electronic signals and vice versa occurs. Recent works have shown how selective sodium and potassium detection can be achieved by direct chemical modification of the polymer. Such modifications introduce ligands with affinity for the cations of interest as substituents on the polymer chain. The present work explores the integration of specifically modified conducting polymers into OECT channels, offering selectivity for zinc cations. Zinc fluxes are crucial in various biological processes, and their reliable detection, especially at low concentrations, is an important challenge. By electropolymerizing a thiophene‐based trimer, modified with a dipicolylamine (DPA) substituent, a conducting polymer‐based OECT is obtained that can selectively detect Zn2+ in the 10−6 to 10−3 mol L−1 concentration range in physiological buffers. [ABSTRACT FROM AUTHOR]

Electromagnetically induced rotation is a key process of many technological systems that are used in daily life, especially for energy conversion. In this context, the Lorentz force‐induced deviation of charges is a crucial physical phenomenon to generate rotation. Herein, they combine the latter with the concept of bipolar electrochemistry to design a wireless magnetoelectrochemical rotor. Such a device can be considered as a wet analog of a conventional electric motor. The main driving force that propels this actuator is the result of the synergy between the charge‐compensating ion flux along a bipolar electrode and an external magnetic field applied orthogonally to the surface of the object. The trajectory of the wirelessly polarized rotor can be controlled by the orientation of the magnetic field relative to the direction of the global electric field, producing a predictable clockwise or anticlockwise motion. Fine‐tuning of the applied electric field allows for addressing conducting objects having variable characteristic lengths. [ABSTRACT FROM AUTHOR]

Cable bacteria are multicellular, filamentous bacteria that use internal conductive fibers to transfer electrons over centimeter distances from donors within anoxic sediment layers to oxygen at the surface. We extracted the fibers and used them as free‐standing bio‐based electrodes to investigate their electrocatalytic behavior. The fibers catalyzed the reversible interconversion of oxygen and water, and an electric current was running through the fibers even when the potential difference was generated solely by a gradient of oxygen concentration. Oxygen reduction as well as oxygen evolution were confirmed by optical measurements. Within living cable bacteria, oxygen reduction by direct electrocatalysis on the fibers and not by membrane‐bound proteins readily explains exceptionally high cell‐specific oxygen consumption rates observed in the oxic zone, while electrocatalytic water oxidation may provide oxygen to cells in the anoxic zone. [ABSTRACT FROM AUTHOR]

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