Curvy surface conformal ultra-thin transfer printed Si optoelectronic penetrating microprobe arrays

Penetrating neural probe arrays are powerful bio-integrated devices for studying basic neuroscience and applied neurophysiology, underlying neurological disorders, and understanding and regulating animal and human behavior. This paper presents a penetrating microprobe array constructed in thin and flexible fashion, which can be seamlessly integrated with the soft curvy substances. The function of the microprobes is enabled by transfer printed ultra-thin Si optoelectronics. As a proof-of-concept device, microprobe array with Si photodetector arrays are demonstrated and their capability of mapping the photo intensity in space are illustrated. The design strategies of utilizing thin polyimide based microprobes and supporting substrate, and employing the heterogeneously integrated thin optoelectronics are keys to accomplish such a device. The experimental and theoretical investigations illustrate the materials, manufacturing, mechanical and optoelectronic aspects of the device. While this paper primarily focuses on the device platform development, the associated materials, manufacturing technologies, and device design strategy are applicable to more complex and multi-functionalities in penetrating probe array-based neural interfaces and can also find potential utilities in a wide range of bio-integrated systems. Soft circuits: silicon microprobe array made penetratingSilicon microprobe vertial array has now been made ultra-thin, flexible and suitable for soft tissue integration. A team led by Cunjiang Yu from University of Houston, USA designs an ultra-thin and flexible 3D penetrating microprobe array that is compatible with soft electronics and tissue interfacing and mapping. The microprobe array is fabricated via transfer printing of ultra-thin silicon circuits onto an ultra-thin polyimide support, followed by iron layer deposition, magnetic actuation and epoxy solidification to make and fix the perpendicular and penetrating probes. This work tackles the problems of the mechanical and geometric mismatch between the soft surfaces and relatively rigid electronic circuits with conventional semiconductor fabrication technologies. It will bring immediate interest in developing multi-functioning and bio-integrated applications.