Vertical Integration Approach for Fabrication of Customizable Neurophysiology Probes

Advancements in neurophysiology research are often limited by the constraints of current tools for interfacing with both the central and peripheral nervous systems. The development of multifunctional, compact probes capable of interfacing with the brain and peripheral organs presents significant challenges, particularly in achieving a balance between multiple functionalities and minimizing device dimensions. Reducing device dimensions, mechanical rigidity, and surgical invasiveness is critical to mitigating tissue damage and immune responses in in vivo studies. Here, we present a scalable fabrication method for flexible, minimally invasive implantable devices integrated with microelectronic chips, such as µLEDs and temperature sensors, designed for diverse applications in brain and peripheral organ neurophysiology. Our vertically integrated approach employs thin-film layers of polyimide, copper, parylene, and silicone on a handling substrate coated with a sacrificial polymer (dextran). Combined with computer-aided design (CAD) and UV direct laser patterning, this method enables rapid prototyping, scalability, and customization of implantable devices with features as small as 40 µm tailored to specific neurophysiological studies. We demonstrate the versatility of our approach through several illustrative examples, including optogenetic probes for neuronal stimulation in the brain and gut, soft patches for inducing thermogenesis in fat tissue, and devices for localized heating and cooling of deep brain regions.