Extreme manufacturing of minimally invasive intracortical neural electrodes

Small and flexible penetrating neural electrodes have recently emerged as a promising technology for both fundamental brain science and advanced brain-computer interfaces. These neural electrodes are designed with exceptional flexibility and adaptability to seamlessly interact with delicate neural tissue, enabling sub-millisecond recording of individual neurons and stimulation of small neuronal clusters in the brain. In this review, we analyze the fundamental physical constraints imposed on electrical neural interfacing and highlight the significant progress achieved by those minimally invasive neural probes over the past decade. Furthermore, we discuss the research needs in manufacturing techniques, materials science, as well as surface functionalization processes for improving the long-term stability and reliability of neural electrodes. Finally, we summarize the emerging trends and outline the technological challenges faced in this rapidly evolving field.