Personal accessories such as glasses and watches that we usually carry in our daily life can yield useful information from the human body, yet most of them are limited to exercise-related parameters or simple heart rates. Since these restricted characteristics might arise from interfaces between the body and items as one of the main reasons, an interface design considering such a factor can provide us with biologically meaningful data. Here, we describe three-dimensional-printed, personalized, multifunctional electronic eyeglasses (E-glasses), not only to monitor various biological phenomena but also to propose a strategy to coordinate the recorded data for active commands and game operations for human–machine interaction (HMI) applications. Soft, highly conductive composite electrodes embedded in the E-glasses enable us to achieve reliable, continuous recordings of physiological activities. UV-responsive, color-tunable lenses using an electrochromic ionic gel offer the functionality of both eyeglass and sunglass modes, and accelerometers provide the capability of tracking precise human postures and behaviors. Detailed studies of electrophysiological signals including electroencephalogram and electrooculogram demonstrate the feasibility of smart electronic glasses for practical use as a platform for future HMI systems.

A strategy of materials synthesis, characteristic evaluations, and manufacturing process for a mechanically elastic, biologically safe silicon‐based dopamine detector that is designed to be completely transient, i.e., dissolved in water and/or biofluids, potentially in the brain after a desired period of operation, is introduced. Use of inexpensive, bioresorbable iron (Fe)‐based nanoparticles (NPs) is one of the attractive choices for efficient catalytic oxidation of dopamine as an alternative for noble, nontransient platinum (Pt) nanoparticles, based on extensive studies of synthesized materials and catalytic reactions. Arrays of transient dopamine sensors validate electrochemical functionality to determine physiological levels of dopamine and to selectively sense dopamine in a variety of neurotransmitters, illuminating feasibilities for a higher level of soft, transient electronic implants integrated with other components of overall system.

Although neurotransmitters are key substances closely related to evaluating degenerative brain diseases as well as regulating essential functions in the body, many research efforts have not been focused on direct observation of such biochemical messengers, rather on monitoring relatively associated physical, mechanical, and electrophysiological parameters. Here, a bioresorbable silicon‐based neurochemical analyzer incorporated with 2D transition metal dichalcogenides is introduced as a completely implantable brain‐integrated system that can wirelessly monitor time‐dynamic behaviors of dopamine and relevant parameters in a simultaneous mode. An extensive range of examinations of molybdenum/tungsten disulfide (MoS2/WS2) nanosheets and catalytic iron nanoparticles (Fe NPs) highlights the underlying mechanisms of strong chemical and target‐specific responses to the neurotransmitters, along with theoretical modeling tools. Systematic characterizations demonstrate reversible, stable, and long‐term operational performances of the degradable bioelectronics with excellent sensitivity and selectivity over those of non‐dissolvable counterparts. A complete set of in vivo experiments with comparative analysis using carbon‐fiber electrodes illustrates the capability for potential use as a clinically accessible tool to associated neurodegenerative diseases.

Underactive bladder or detrusor underactivity (DUA), that is, not being able to micturate, has received less attention with little research and remains unknown or limited on pathological causes and treatments as opposed to overactive bladder, although the syndrome may pose a risk of urinary infections or life-threatening kidney damage. Here, we present an integrated expandable electronic and optoelectronic complex that behaves as a single body with the elastic, time-dynamic urinary bladder with substantial volume changes up to ~300%. The system configuration of the electronics validated by the theoretical model allows conformal, seamless integration onto the urinary bladder without a glue or suture, enabling precise monitoring with various electrical components for real-time status and efficient optogenetic manipulation for urination at the desired time. In vivo experiments using diabetic DUA models demonstrate the possibility for practical uses of high-fidelity electronics in clinical trials associated with the bladder and other elastic organs.

Recent advances in the engineering or strategy of materials and device design have established ultrathin, soft, lightweight, and skin-conformable characteristics in wearable/implantable electronic systems, allowing precise, long-term monitoring of biological signals from skin/internal organs while reducing signal artifacts upon daily body motions or other external effects. Such a soft, flexible platform offers an opportunity capable of recording and analyzing diverse physical, chemical, and electrophysiological parameters for clinically useful information in the effective prevention, treatment, and management of illness as well as the preservation of physical and mental well-being. Combination with other peculiar functions such as bioresorbable and self-healing properties can enhance the biosafety/reliability of devices and realize unprecedented applications in the fields of biology and medicine or other areas of interest. This Review summarizes the underlying mechanisms of materials science in terms of a mechanical balance between devices and biological structures, discusses the latest biomedical applications with a focus on technological advances and significance, and concludes with an overview of current challenging points and perspectives for future research directions in wearable/implantable electronics.