Finite element analysis of electric field distribution during direct current stimulation of the spinal cord: Implications for device design

Triggerable Patches for Medical Applications

Medical patches have garnered increasing attention in recent decades for several diagnostic and therapeutic applications. Advancements in material science, manufacturing technologies, and bioengineering have significantly widened their functionalities, rendering them highly versatile platforms for wearable and implantable applications. Of particular interest are triggerable patches designed for drug delivery and tissue regeneration purposes, whose action can be controlled by an external signal. Stimuli-responsive patches are particularly appealing as they may enable a high level of temporal and spatial control over the therapy, allowing high therapeutic precision and the possibility to adjust the treatment according to specific clinical and personal needs. This review aims to provide a comprehensive overview of the existing extensive literature on triggerable patches, emphasizing their potential for diverse applications and highlighting the strengths and weaknesses of different triggering stimuli. Additionally, the current open challenges related to the design and use of efficient triggerable patches, such as tuning their mechanical and adhesive properties, ensuring an acceptable trade-off between smartness and biocompatibility, endowing them with portability and autonomy, accurately controlling their responsiveness to the triggering stimulus and maximizing their therapeutic efficacy, are reviewed.

Guest Editorial: Implantable bioelectronics

The realm of implantable bioelectronics represents a frontier in medical science, merging technology, biology, and medicine to innovate treatments that enhance, restore, or monitor physiological functions. This field has yielded devices like cochlear implants, cardiac pacemakers, deep brain stimulators, and vagus nerve stimulators, each designed to address a specific health condition, ranging from sensorineural hearing loss to chronic pain, neurological disorders, and heart rhythm irregularities. Such devices underscore the potential of bioelectronics to significantly improve patient outcomes and quality of life. Recent technological breakthroughs in materials science, nanotechnology, and microfabrication have enabled the development of more sophisticated, smaller, and biocompatible bioelectronic devices. However, the field also encounters challenges, particularly in extending the capabilities of devices such as retinal prostheses, which aim to restore vision but currently offer limited visual acuity. Research in implantable bioelectronics is highly timely, driven by an aging global population with a growing prevalence of chronic diseases that could benefit from these technologies. The convergence of societal health needs, advancing technological capabilities, and a supportive ecosystem for innovation marks this era as pivotal for bioelectronic research.

Wireless control of nerve growth using bipolar electrodes: a new paradigm in electrostimulation

Electrical activity underpins all life, but is most familiar in the nervous system, where long range electrical signalling is essential for function. When this is lost (e.g., traumatic injury) or it becomes inefficient (e.g., demyelination), the use of external fields can compensate for at least some functional deficits. However, its potential to also promote biological repair at the cell level is underplayed despite abundant in vitro evidence for control of neuron growth. This perspective article considers specifically the emerging possibility of achieving cell growth through the interaction of external electric fields using conducting materials as unwired bipolar electrodes, and without intending stimulation of neuron electrical activity to be the primary consequence. The use of a wireless method to create electrical interactions represents a paradigm shift and may allow new applications in vivo where physical wiring is not possible. Within that scheme of thought an evaluation of specific materials and their dynamic responses as bipolar unwired electrodes is summarized and correlated with changes in dynamic nerve growth during stimulation, suggesting possible future schemes to achieve neural growth using bipolar unwired electrodes with specific characteristics. This strategy emphasizes how nerve growth can be encouraged at injury sites wirelessly to induce repair, as opposed to implanting devices that may substitute the neural signals.