Hierarchically structured materials, inspired by sophisticated structures found in nature, are finding increasing applications in a variety of fields. Here, we describe the fabrication of wrinkled gold nanoparticle films, which leverage the structural tunability of gold nanoparticles to program the wavelength and amplitude of gold wrinkles. We have carefully examined the structural evolution and tuning of these wrinkled surfaces through varying nanoparticle parameters (diameter, number of layers, density) and substrate parameters (number of axes constrained during wrinkling) through scanning electron microscopy and cross-sectional transmission electron microscopy. It is found that nanoparticle layers of sufficient density are required to obtain periodical wrinkled structures. It was also found that tuning the nanoparticle diameter and number of layers can be used to program the wrinkle wavelength and amplitude by changing the film thickness and mechanical properties. This dual degree of tunability, not previously seen with continuous films, allows us to develop one of the smallest wrinkles developed to date with tunability in the sub-100 nm regime. The effect of the induced structural tunability on the enhancement of the intensity of the 4-mercaptopyridine Raman spectra is also studied through the application of these devices as substrates for surface-enhanced Raman spectroscopy (SERS), where wrinkling proves to be an effective method for enhancing the SERS signal in cases where there is an inherently low density of gold nanoparticles.
Three-dimensional electrodes that are controllable over multiple lengthscales are very important for use in bioanalytical systems that integrate solid-phase devices with solution-phase samples. Here we present a fabrication method based on all-solution-processing and thin film wrinkling using smart polymers that is ideal for rapid prototyping of tunable three-dimensional electrodes and is extendable to large volume manufacturing. Although all-solution-processing is an attractive alternative to vapor-based techniques for low-cost manufacturing of electrodes, it often results in films suffering from low conductivity and poor substrate adhesion. These limitations are addressed here by using a smart polymer to create a conformal layer of overlapping wrinkles on the substrate to shorten the current path and embed the conductor onto the polymer layer. The structural evolution of these wrinkled electrodes, deposited by electroless deposition onto a nanoparticle seed layer, is studied at varying deposition times to understand its effects on structural parameters such as porosity, wrinkle wavelength and height. Furthermore, the effect of structural parameters on functional properties such as electro-active surface area and surface-enhanced Raman scattering is investigated. It is found that wrinkling of electroless-deposited thin films can be used to reduce sheet resistance, increase surface area, and enhance the surface-enhanced Raman scattering signal.
Objective: The objective of this study is to determine the characteristics and frequency of intraoperative safety threats and resilience supports using a human factors measurement tool. Background: Human factors analysis can provide insight into how system elements contribute to intraoperative adverse events. Empiric evidence on safety threats and resilience in surgical practice is lacking. Methods: A cross-sectional study of 24 patients undergoing elective laparoscopic general surgery at a single center in the Netherlands from May to November, 2017 was conducted. Video, audio, and patient physiologic data from all included procedures were obtained through a multichannel synchronized recording device. Trained analysts reviewed the recordings and coded safety threats and resilience supports. The codes were categorized into 1 of 6 categories (person, task, tools and technology, physical environment, organization, and external environment). Results: A median of 14 safety threats [interquartile range (IQR) 11-16] and 12 resilience supports (IQR 11-16) were identified per case. Most safety threat codes (median 9, IQR 7-12) and resilience support codes (median 10, IQR 7-12) were classified in the person category. The organization category contained a median of 2 (IQR 1-2) safety threat codes and 2 (IQR 2-3) resilience support codes per case. The tools and technology category contributed a small number of safety threats (median 1 per case, IQR 0-1), but rarely provided resilience support. Conclusions: Through a detailed human factors analysis of elective laparoscopic general surgery cases, this study provided a quantitative analysis of the existing safety threats and resilience supports in a modern endoscopic operating room.
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