Monitoring and modulating the diversity of signals used by neurons and glia in a closed-loop fashion is necessary to establish causative links between biochemical processes within the nervous system and observed behaviours. As developments in neural interface hardware strive to keep pace with rapid progress in genetically encoded and synthetic reporters/modulators of neural activity, the integration of multiple functional features becomes a key requirement and a pressing challenge in the field of neural engineering. Electrical, optical, and chemical approaches have been used to manipulate and record neuronal activity in vivo, with a recent focus on technologies that both integrate multiple modes of interaction with neurons into a single device and enable bidirectional communication with neural circuits with enhanced spatiotemporal precision. These technologies are not only facilitating a greater understanding of the brain, spinal cord and peripheral circuits in the context of health and disease, but also informing the development of future closed-loop therapies for neurological, neuro-immune and neuroendocrine conditions.

In response to pandemic-related shortages in medical supplies, the authors use an institutional review board-supervised research protocol to clinically test a 3Dprinted face shield in a hospital emergency department. This allowed a major academic medical center to incorporate locally manufactured personal protective equipment into the care of COVID-19 patients.