Batch Transfer Printing of Small-Size Silicon Nano-Films with Flat Stamp

Silicon nano-film is essential for the rapidly developing fields of nanoscience and flexible electronics, due to its compatibility with the CMOS process. Viscoelastic PDMS material can adhere to Si, SiO2, and other materials via intermolecular force and play a key role in flexible electronic devices. Researchers have studied many methods of transfer printing silicon nano-films based on PDMS stamps with pyramid microstructures. However, only large-scale transfer printing processes of silicon nano-films with line widths above 20 μm have been reported, mainly because the distribution of pyramid microstructures proposes a request on the size of silicon nano-films. In this paper, The PDMS base to the curing agent ratio affects the adhesion to silicon and enables the transfer, without the need for secondary alignment photolithography, and a flat stamp has been used during the transfer printing, with no requirement for the attaching pressure and detaching speed. Transfer printing of 20 μm wide structures has been realized, while the success rate is 99.3%. The progress is promising in the development of miniature flexible sensors, especially flexible hydrophone.

Temperature-Sensing Inks Using Electrohydrodynamic Inkjet Printing Technology

Temperature measurement is very important for thermal control, which is required for the advancement of mechanical and electronic devices. However, current temperature sensors are limited by their inability to measure curved surfaces. To overcome this problem, several methods for printing flexible substrates were proposed. Among them, electrohydrodynamic (EHD) inkjet printing technology was adopted because it has the highest resolution. Since EHD inkjet printing technology is limited by the type of ink used, an ink with temperature-sensing properties was manufactured for use in this printer. To confirm the applicability of the prepared ink, its resistance characteristics were investigated, and the arrangement and characteristics of the particles were observed. Then, the ink was printed using the EHD inkjet approach. In addition, studies of the meniscus shapes and line widths of the printed results under various conditions confirmed the applicability of the ink to the EHD inkjet printing technology and the change in its resistance with temperature.

Insights into Protein Dynamics from ¹⁵N-¹H HSQC

Protein dynamic information is customarily extracted from 15N NMR spin-relaxation experiments. These experiments can only be applied to (small) proteins that can be dissolved to high concentrations. However, most proteins of interest to the biochemical and biomedical community are large and relatively insoluble. These proteins often have functional conformational changes, and it is particularly regretful that these processes cannot be supplemented by dynamical information from NMR. We ask here whether (some) dynamic information can be obtained from the 1H line widths in 15N-1H HSQC spectra. Such spectra are widely available, also for larger proteins. We developed computer programs to predict amide proton line widths from (crystal) structures. We aim to answer the following basic questions: is the 1H linewidth of a HSQC cross peak smaller than average because its 1H nucleus has few dipolar neighbors, or because the resonance is motionally narrowed? Is a broad line broad because of conformational exchange, or because the 1H nucleus resides in a dense proton environment? We calibrate our programs by comparing computational and experimental results for GB1 (58 residues). We deduce that GB1 has low average 1HN order parameters (0.8), in broad agreement with what was found by others from 15N relaxation experiments (Idiyatullin et al., 2003). We apply the program to the BPTI crystal structure and compare the results with a 15N-1H HSQC spectrum of BPTI (56 residues) and identify a cluster of conformationally broadened 1HN resonances that belong to an area, for which millisecond dynamics has been previously reported from 15N relaxation data (Szyperski et al., J. Biomol. NMR 3, 151-164, 1993). We feel that our computational approach is useful to glean insights into the dynamical properties of larger biomolecules for which high-quality 15N relaxation data cannot be recorded.