Paper‐based devices are said to be easy to make and use. It is true, if you know how. We hope this Review will help people that are new to the field but also those more experienced who want to add some new functionalities to their systems. Tips and common pitfalls are provided in each section as well as references to recommended reading material. Paper devices have been in development for around two millennia, in one form or the other, and ingenious solutions can be borrowed from the world of paper toys, or closer to electrochemistry paper electronics developed from the 1960’ onwards. Small projects on such systems can become a good practice even in laboratories not working on disposable sensors and low‐cost diagnostics as paper‐based devices are a great way to introduce new students to lab work and teach problem solving. We would also like to show that paper indeed has real life applications and is more than just a good keyword but with the number of publications on the topic, it might not always be easy to distinguish the advances from the background noise.

Excellent electronic and optical properties make indium tin oxide (ITO) an attractive electrode substrate. Despite the commercial availability of high-quality ITO and some low-cost methods for direct deposition being in use by now, the definition of patterns is still a concern. Putting its popularity and extensive usage aside, the manufacturing of ITO electrodes so far lacks a rapid, highly reproducible, flexible, cost-effective, easy patterning process that could surpass difficult, time-consuming techniques such as lithography. A cost-effective method based on CO2 laser irradiation for preparing ITO microelectrodes and electrode arrays is presented herein. Electrodes of different sizes and shapes were examined to identify the performance of the proposed methods. Direct ablation of the ITO layer was optimized for rectangular electrodes of 25, 50, and 100 µm width, while laser cutting of scotch tape stencils and subsequent wet etching were used to create circular electrodes with a diameter of 1.75mm. Together, both methods form a complete toolbox, which allows for low-cost and fast fabrication of ITO electrodes for wide variety of applications. A multielectrode array system consisting 8 of these circular electrodes was fashioned, fabricated, assembled and tested. The ITO electrodes were characterized electrochemically and as an example application they were used for monitoring anchoring behavior of HeLa and HepG2 cell cultures through cell-based electrochemical impedance technique.

Nowadays, multi-domain systems are crucial for accurate measurements since they improve error avoidance in empirical observations by supplementing one domain with the other. Such an approach also yields more useful information about the sample under study. In this work, we present the results obtained from a sensing system composed of a microcavity inline Mach-Zehnder interferometer (μIMZI) combined with indium tin oxide (ITO) electrodes, which is the first approach to two-domain, real-time, and label-free observation of cell behavior. The µIMZI structure was manufactured with a femtosecond laser ablation process in the side surface of single-mode optical fiber. It is susceptible to refractive index (RI) change within its volume, i.e., hundreds of picolitres. The μIMZI sensitivity to RI reaches over 15,000 nm/RIU. The μIMZI was attached to the glass plate with eight ITO electrodes formed using laser irradiation. This optical and electrochemical domain system was used for cell medium measurements, followed by one hour of HepG2 cells monitoring. Finally, trypsin was added to the solution, and its effects on the HepG2 cells were investigated optically and electrochemically. The presented monitoring setup and obtained results are proof of concept for a multi-domain cell monitoring system.

The influence of high pressure (in the kbar region) on the outcome of the Au(I)-catalyzed cycloisomerization of 1,6- and 1,7-enynes is presented. The positive effect of pressure is particularly marked for reactions involving sterically biased substrates (e.g. 1,6-enynes bearing atert-butyl substituent at the alkyne moiety) and the challenging cyclization of internal 1,7-enynes.