Wearable healthcare devices have garnered substantial interest for the realization of personal health management by monitoring the physiological parameters of individuals. Attaining the integrity between the devices and the biological interfaces is one of the greatest challenges to achieving high‐quality body information in dynamic conditions. Liquid metals, which exist in the liquid phase at room temperatures, are advanced intensively as conductors for deformable devices because of their excellent stretchability and self‐healing ability. The unique surface chemistry of liquid metals allows the development of various sensors and devices in wearable form. Also, the biocompatibility of liquid metals, which is verified through numerous biomedical applications, holds immense potential in uses on the surface and inside of a living body. Here, the recent progress of liquid metal‐based wearable electronic devices for healthcare with respect to the featured properties and the processing technologies is discussed. Representative examples of applications such as biosensors, neural interfaces, and a soft interconnection for devices are reviewed. The current challenges and prospects for further development are also discussed, and the future directions of advances in the latest research are explored.

Herein, we present an unconventional method for multimodal characterization of three-dimensional cardiac organoids. This method can monitor and control the mechanophysiological parameters of organoids within a single device. In this method, local pressure distributions of human-induced pluripotent stem-cell-derived cardiac organoids are visualized spatiotemporally by an active-matrix array of pressure-sensitive transistors. This array is integrated with three-dimensional electrodes formed by the high-resolution printing of liquid metal. These liquid-metal electrodes are inserted inside an organoid to form the intraorganoid interface for simultaneous electrophysiological recording and stimulation. The low mechanical modulus and low impedance of the liquid-metal electrodes are compatible with organoids’ soft biological tissue, which enables stable electric pacing at low thresholds. In contrast to conventional electrophysiological methods, this measurement of a cardiac organoid’s beating pressures enabled simultaneous treatment of electrical therapeutics using a single device without any interference between the pressure signals and electrical pulses from pacing electrodes, even in wet organoid conditions.

Organoids refer to 3D stem cells that have been developed to model neurological disorders in vitro. Typically, brain and heart organoids have gained interest for their potential to truly mimic the functional ability of real organs. Morphological analysis methods using immunostaining and slicing of the organoids are explored extensively over the past decade to evaluate the structures and functions of organoids. However, the destructiveness of these methods limits real‐time monitoring of the dynamic responses of the organoids. Therefore, electrophysiological functional analysis of organoids with minimally invasive forms can be a key solution to an improved understanding of the nature of complex organoids. Herein, the latest advances in the recording platforms are reviewed and a comprehensive study of considerations regarding electrophysiological factors is provided. Furthermore, current challenges are discussed along with prospects for next‐generation electrophysiological analysis of brain and heart organoids.

Electrical stimulation as a therapeutic approach is widely applicable in terms of target tissues or target effects. This method can be an alternative to conventional therapies for patients who are resistant to drugs or are ineligible for surgical operations. In addition, as researchers have actively studied how to adjust the parameters for electrical stimulation in order to improve effectiveness, many patients have already received treatments with electrical stimulation. With respect to devices for electrical stimulation, recent studies are focused on developing reliability for safe and long‐term operations. From the point of view of engineers, a comprehensive understanding of how electrical stimulation modulates the biological system is essential to develop advanced strategies that provide effective therapeutic results. Herein, the fundamental mechanisms for delivering electrical stimulation on biological tissues are reviewed along with the requirements that need to be qualified by the electrodes. Furthermore, the latest advances in electrical stimulation devices are discussed followed by an introduction of representative applications of therapeutic electrical stimulation.