Highly sensitive electrochemical detection of living cells based on diamond microelectrode arrays

We designed boron-doped nanocrystalline diamond microelectrode arrays（BNCD-MEAs） with 16 channels for the bioanalysis of multicellular samples, which could be readily adapted for a highly sensitive detection of H2 O2[2_TD$IF]released from stimulated cells by ascorbic acid（AA）. Our observations demonstrated that the as-prepared diamond microelectrode arrays could be utilized to distinguish cancer cells from normal cells, and the amperometric study showed the considerable differences in the currents, indicating that the related Hep G2 cancer cells could release more H2 O2 than that of L02 normal cells. This supports the possibility to use diamond-based MEAs for rapid cancer cell detection in future clinic applications.

Highly efficient passive Tesla valves for microfluidic applications

A multistage optimization method is developed yielding Tesla valves that are efficient even at low flow rates,characteristic,e.g.,for almost all microfluidic systems,where passive valves have intrinsic advantages over active ones.We report on optimized structures that show a diodicity of up to 1.8 already at flow rates of 20μl s^(−1) corresponding to a Reynolds number of 36.Centerpiece of the design is a topological optimization based on the finite element method.It is set-up to yield easy-to-fabricate valve structures with a small footprint that can be directly used in microfluidic systems.Our numerical two-dimensional optimization takes into account the finite height of the channel approximately by means of a so-called shallow-channel approximation.Based on the threedimensionally extruded optimized designs,various test structures were fabricated using standard,widely available microsystem manufacturing techniques.The manufacturing process is described in detail since it can be used for the production of similar cost-effective microfluidic systems.For the experimentally fabricated chips,the efficiency of the different valve designs,i.e.,the diodicity defined as the ratio of the measured pressure drops in backward and forward flow directions,respectively,is measured and compared to theoretical predictions obtained from full 3D calculations of the Tesla valves.Good agreement is found.In addition to the direct measurement of the diodicities,the flow profiles in the fabricated test structures are determined using a two-dimensional microscopic particle image velocimetry(μPIV)method.Again,a reasonable good agreement of the measured flow profiles with simulated predictions is observed.

Tip-and Laser-based 3D Nanofabrication in Extended Macroscopic Working Areas

The field of optical lithography is subject to intense research and has gained enormous improvement.However,the effort necessary for creating structures at the size of 20 nm and below is considerable using conventional technologies.This effort and the resulting financial requirements can only be tackled by few global companies and thus a paradigm change for the semiconductor industry is conceivable:custom design and solutions for specific applications will dominate future development(Fritze in:Panning EM,Liddle JA(eds)Novel patterning technologies.International society for optics and photonics.SPIE,Bellingham,2021.https://doi.org/10.1117/12.2593229).For this reason,new aspects arise for future lithography,which is why enormous effort has been directed to the development of alternative fabrication technologies.Yet,the technologies emerging from this process,which are promising for coping with the current resolution and accuracy challenges,are only demonstrated as a proof-of-concept on a lab scale of several square micrometers.Such scale is not adequate for the requirements of modern lithography;therefore,there is the need for new and alternative cross-scale solutions to further advance the possibilities of unconventional nanotechnologies.Similar challenges arise because of the technical progress in various other fields,realizing new and unique functionalities based on nanoscale effects,e.g.,in nanophotonics,quantum computing,energy harvesting,and life sciences.Experimental platforms for basic research in the field of scale-spanning nanomeasuring and nanofabrication are necessary for these tasks,which are available at the Technische Universitiit Ilmenau in the form of nanopositioning and nanomeasuring(NPM)machines.With this equipment,the limits of technical structurability are explored for high-performance tip-based and laser-based processes for enabling real 3D nanofabrication with the highest precision in an adequate working range of several thousand cubic millimeters.