Phase-separated porous nanocomposite with ultralow percolation threshold for wireless bioelectronics.

Realizing the full potential of stretchable bioelectronics in wearables, biomedical implants and soft robotics necessitates conductive elastic composites that are intrinsically soft, highly conductive and strain resilient. However, existing composites usually compromise electrical durability and performance due to disrupted conductive paths under strain and rely heavily on a high content of conductive filler. Here we present an in situ phase-separation method that facilitates microscale silver nanowire assembly and creates self-organized percolation networks on pore surfaces. The resultant nanocomposites are highly conductive, strain insensitive and fatigue tolerant, while minimizing filler usage. Their resilience is rooted in multiscale porous polymer matrices that dissipate stress and rigid conductive fillers adapting to strain-induced geometry changes. Notably, the presence of porous microstructures reduces the percolation threshold (Vc = 0.00062) by 48-fold and suppresses electrical degradation even under strains exceeding 600%. Theoretical calculations yield results that are quantitatively consistent with experimental findings. By pairing these nanocomposites with near-field communication technologies, we have demonstrated stretchable wireless power and data transmission solutions that are ideal for both skin-interfaced and implanted bioelectronics. The systems enable battery-free wireless powering and sensing of a range of sweat biomarkers-with less than 10% performance variation even at 50% strain. Ultimately, our strategy offers expansive material options for diverse applications.

Imaging neuro-urodynamics of mouse major pelvic ganglion with a micro-endoscopic approach.

Postganglionic neurons of the autonomic nervous system lie outside of the central nervous system and innervate specific target effectors such as organs or glands. The major pelvic ganglion (MPG) is one such ganglion that plays a significant role in controlling bladder function in rodents. However, because of technical and physical constraints in recording electrophysiological signals from these neurons in vivo, the functional neural activity in MPG is mostly unknown. Transgenic animal models expressing genetically encoded calcium indicators now provide opportunities to monitor the activity of populations of neurons in vivo to overcome these challenges related to traditional electrophysiological methods. However, like many peripheral neurons, the MPG is not conducive to conventional fluorescent microscopy techniques, as it is located in the pelvic cavity, thus limiting robust optical access by benchtop microscopes. Here, we present an endoscopic approach based on a custom miniscope system (UCLA V3) that allows for effective in vivo monitoring of neural activity in the MPG for the first time. We show that our imaging approach can monitor activity of hundreds of MPG neurons simultaneously during the filling and emptying of the bladder in a urethane-anesthetized transgenic mouse line expressing GCaMP6s in cholinergic MPG neurons. By using custom analysis scripts, we isolated the activity of hundreds of individual neurons and show that populations of neurons have distinct phasic activation patterns during sequential bladder filling and voiding events. Our imaging approach can be adapted to record activity from autonomic neurons across different organs and systems in both healthy and disease models.NEW & NOTEWORTHY The functional activity and information processing within autonomic ganglia is mostly unknown because of technical and physical constraints in recording electrophysiological signals from these neurons in vivo. Here, we use a micro-endoscopic approach to measure in vivo functional activity patterns from a population of autonomic neurons controlling bladder function for the first time. This approach can be adapted to record activity from autonomic neurons across different organs and systems in both healthy and disease models.

The Drosophila Gr28bD product is a non-specific cation channel that can be used as a novel thermogenetic tool.

Extrinsic control of single neurons and neuronal populations is a powerful approach for understanding how neural circuits function. Adding new thermogenetic tools to existing optogenetic and other forms of intervention will increase the complexity of questions that can be addressed. A good candidate for developing new thermogenetic tools is the Drosophila gustatory receptor family, which has been implicated in high-temperature avoidance behavior. We examined the five members of the Gr28b gene cluster for temperature-dependent properties via three approaches: biophysical characterization in Xenopus oocytes, functional calcium imaging in Drosophila motor neurons, and behavioral assays in adult Drosophila. Our results show that Gr28bD expression in Xenopus oocytes produces a non-specific cationic current that is activated by elevated temperatures. This current is non-inactivating and non-voltage dependent. When expressed in Drosophila motor neurons, Gr28bD can be used to change the firing pattern of individual cells in a temperature-dependent fashion. Finally, we show that pan-neuronal or motor neuron expression of Gr28bD can be used to alter fruit fly behavior with elevated temperatures. Together, these results validate the potential of the Gr28bD gene as a founding member of a new class of thermogenetic tools.