The interface between cells and non-biological surfaces regulates cell attachment, chronic tissue responses, and ultimately the success of medical implants or biosensors. Clinical and laboratory studies show that topological features of the surface profoundly influences cellular responses, e.g. titanium surfaces with nano- and microtopographical structures enhance osteoblast attachment and host-implant integration as compare to smooth surface. To understand how cells and tissues respond to different topographical features, it is of critical importance to directly visualize the cell-materials interface at the relevant nanometer length scale. Here, we present a new method for in situ examination of the cell-to-material interface at any desired location, based on focused-ion beam milling and scanning electron microscopy imaging (FIB-SEM) to resolve the cell membrane-to-material interface with 10 nm resolution. By examining how cell membranes interact with topographical features such as nanoscale protrusions or invaginations, we discovered that the cell membrane readily deforms inward and wraps around protruding structures, but hardly deforms outward to contour invaginating structures. This asymmetric membrane response (inward vs. outward deformation) causes the cleft width between the cell membrane and the nanostructure surface to vary for more than an order of magnitude. Our results suggest that surface topology is a crucial consideration for the development of medical implants or biosensors whose performances are strongly influenced by the cell-to-material interface. We anticipate that the method can be used to explore the direct interaction of cells/tissue with medical devices such as metal implants in the future.

Inkjet printing is an attractive method for cost-effective additive manufacturing of electronic devices. Especially for applications where disposable sensor systems are of interest, it is a promising tool since it enables the production of low-cost and flexible devices. In this work, we report the fabrication of a disposable microelectrode array (MEA) using solely inkjet printing technology. The MEAs were fabricated with two different functional inks, a self-made gold ink to print conductive feedlines and electrodes and a polymer-based ink to add a dielectric layer for insulation of the feedlines. We printed different MEA designs of up to 64 electrodes with a minimum lateral spacing of 200 μm and a minimum electrode diameter of ∼31 μm. As a proof-of-concept, extracellular recordings of action potentials from cardiomyocyte-like HL-1 cells were performed using the all-printed devices. Furthermore, we stimulated the cells during the recordings with noradrenaline, which led to an increase in the recorded beating frequency of the cells. The results demonstrate the feasibility of inkjet printing gold MEAs for cell-based bioelectronics.

Gaining better understanding of the human brain using chip‐based devices and promoting the recovery of lost biological functionality through implants are long pursued endeavors driven by advances in material science, bioelectronics, and the advancing silicon technology. While conventional bioelectronic and neuroelectronic devices typically rely on cleanroom‐based processing, a rapid prototyping technique is proposed that is based on high‐resolution inkjet printing featuring nanoporous carbon electrodes that yield excellent cell–chip coupling. This study aims to overcome two major limitations of conventional approaches that make the development of neuroelectronic devices very challenging and limit a wider use within the research community as well as industry: high costs and lack of rapid prototyping capabilities. These challenges are addressed with an all‐printed, high‐resolution approach that makes use of flexible polymer substrates and is fabricated on a fully digital printing platform. The manufacturing of a chip consumes less than 60 min and costs a few cents per chip. This study introduces nanoporous carbon as a cell‐interfacing electrode material that features outstanding properties for extracellular recording of action potentials and stimulation indicating that the printed carbon chips have the means to be used as a versatile neuroelectronic tool for in vitro and in vivo studies.

18 The interface between biological cells and non-biological surfaces profoundly influences