3D Printing of Inertial Microfluidic Devices.

Inertial microfluidics has been broadly investigated, resulting in the development of various applications, mainly for particle or cell separation. Lateral migrations of these particles within a microchannel strictly depend on the channel design and its cross-section. Nonetheless, the fabrication of these microchannels is a continuous challenging issue for the microfluidic community, where the most studied channel cross-sections are limited to only rectangular and more recently trapezoidal microchannels. As a result, a huge amount of potential remains intact for other geometries with cross-sections difficult to fabricate with standard microfabrication techniques. In this study, by leveraging on benefits of additive manufacturing, we have proposed a new method for the fabrication of inertial microfluidic devices. In our proposed workflow, parts are first printed via a high-resolution DLP/SLA 3D printer and then bonded to a transparent PMMA sheet using a double-coated pressure-sensitive adhesive tape. Using this method, we have fabricated and tested a plethora of existing inertial microfluidic devices, whether in a single or multiplexed manner, such as straight, spiral, serpentine, curvilinear, and contraction-expansion arrays. Our characterizations using both particles and cells revealed that the produced chips could withstand a pressure up to 150 psi with minimum interference of the tape to the total functionality of the device and viability of cells. As a showcase of the versatility of our method, we have proposed a new spiral microchannel with right-angled triangular cross-section which is technically impossible to fabricate using the standard lithography. We are of the opinion that the method proposed in this study will open the door for more complex geometries with the bespoke passive internal flow. Furthermore, the proposed fabrication workflow can be adopted at the production level, enabling large-scale manufacturing of inertial microfluidic devices

How To Quantify the Efficiency Potential of Neat Perovskite Films: Perovskite Semiconductors with an Implied Efficiency Exceeding 28.

Perovskite photovoltaic (PV) cells have demonstrated power conversion efficiencies (PCE) that are close to those of monocrystalline silicon cells; however, in contrast to silicon PV, perovskites are not limited by Auger recombination under 1-sun illumination. Nevertheless, compared to GaAs and monocrystalline silicon PV, perovskite cells have significantly lower fill factors due to a combination of resistive and non-radiative recombination losses. This necessitates a deeper understanding of the underlying loss mechanisms and in particular the ideality factor of the cell. By measuring the intensity dependence of the external open-circuit voltage and the internal quasi-Fermi level splitting (QFLS), the transport resistance-free efficiency of the complete cell as well as the efficiency potential of any neat perovskite film with or without attached transport layers are quantified. Moreover, intensity-dependent QFLS measurements on different perovskite compositions allows for disentangling of the impact of the interfaces and the perovskite surface on the non-radiative fill factor and open-circuit voltage loss. It is found that potassium-passivated triple cation perovskite films stand out by their exceptionally high implied PCEs > 28%, which could be achieved with ideal transport layers. Finally, strategies are presented to reduce both the ideality factor and transport losses to push the efficiency to the thermodynamic limit

Prioritizing actions and outcomes for community-based future manufacturing workforce development and education

Rapid innovations in manufacturing process technology, information technology, and systems technology have led to simultaneous concerns about labor displacements and skills shortages. To address these concerns, the key challenges for educating and training the current and future workforce should be identified and the specific activities leading to the design of new manufacturing career pathways should be defined. Thus, the objective of this article is to define and prioritize the necessary activities and short- to long-term outcomes that will aid in developing high-skill career pathways that will positively impact children and families, students and teachers, and future workers. Expert perspectives from industry and academia have been analysed through two lenses: education (primary/secondary, technical, and university levels) and policy/innovation. The nominal group technique (NGT) is applied in this research to capture these perspectives, which enabled the generation of ideas followed by discussion and ranking by the experts. This approach encourages participation and avoids the associated drawbacks of typical group interactions. As a result, prioritized activities, short-term outcomes, and policy ideas to introduce children and families, students and teachers, and future workers to careers in advanced manufacturing are presented for each lens of focus. In addition, inputs from experts were captured to discuss desired medium- to long-term outcomes. In conclusion, this article summarizes the key findings from the study.This is a manuscript of an article published as Haapala KR, Raoufi K, Kim K-Y, et al. Prioritizing actions and outcomes for community-based future manufacturing workforce development and education. Journal of Integrated Design and Process Science. 2022;26(3-4):415-441. doi:10.3233/JID-220007

Toward Understanding the Built in Field in Perovskite Solar Cells through Layer by Layer Surface Photovoltage Measurements

The built in voltage VBI is a key parameter for solar cell operation, yet in perovskite solar cells the distribution, magnitude, and origin of the VBI remains poorly understood. In this work, we systematically studied the VBI in pin type perovskite solar cells based on different hole transport layers TLs . To this end, we determine the surface photovoltage SPV of partial and complete device stacks layerby layer by measuring the work function WF under dark and light equivalent AM1.5G conditions with Kelvin probe KP and photoemission spectroscopy UPS measurements in 3 different laboratories. We demonstrate that the SPV increases upon the addition of each additional layer until it equals the open circuit voltage VOC of the full device. This suggests that both the electron and hole transport layer HTL ETL enlarge the SPV, by improving the separation of photogenerated carriers. Yet, the contribution of both transport layers to the total SPV of the device is small in the range of amp; 8776;100 to 200 meV and the largest contribution to the SPV originates from the top metal electrode amp; 8776;500 meV . The results suggest that the VBI of pin type perovskite solar cells is largely a result of the workfunction difference of the electrodes. With regard to films or incomplete cell stacks , our simulations can reproduce the measured SPV, and measured quasi Fermi level splitting gt;VOC in partial cell stacks without a significant internal field consistent with the experimental data. This work establishes layer by layer SPV measurements, which are easily accessible, as a key tool for understanding device performance and internal energetics, similar to layer by layer QFLS measurement

Lutein and lutein esters in wheat during grain development and post-harvest storage

I R Soriano, H Y Law, N Raoufi-Rad and D J Mareshttp://meeting.aaccnet.org/cerealchem08/default.ht