Micro and Nano Engineering最新文献

{"title":"Laser-engraved holograms as entropy source for random number generators","authors":"Christos Tselios ,&nbsp;Anastasios Tsakas ,&nbsp;Simone Mazzucato ,&nbsp;Christina Politi (Tanya) ,&nbsp;Panagiotis Rizomiliotis ,&nbsp;Dimitris Alexandropoulos","doi":"10.1016/j.mne.2024.100290","DOIUrl":"10.1016/j.mne.2024.100290","url":null,"abstract":"<div><div>Our study introduces a novel approach to true random number generation (TRNG) using speckle patterns generated by laser-engraved holograms on carbon fiber-reinforced polymer (CFRP) composite substrates. Unlike previous methods, our approach simplifies the process by generating the necessary image dataset from a single microscope image of the engraved hologram. We achieve a high extraction ratio of 76 %, demonstrating the effectiveness of our TRNG. Moreover, our method successfully passes rigorous statistical tests proposed by the National Institute of Standards and Technology (NIST), indicating its suitability for cryptographic and secure system applications. This work offers promising implications for enhancing security in various domains, from secure communication networks to IoT devices.</div></div>","PeriodicalId":37111,"journal":{"name":"Micro and Nano Engineering","volume":"25 ","pages":"Article 100290"},"PeriodicalIF":2.8,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Developments in the design and microfabrication of photovoltaic retinal implants","authors":"Pratik Kusumanchi ,&nbsp;Stephan Sylvest Keller ,&nbsp;Rasmus Schmidt Davidsen","doi":"10.1016/j.mne.2024.100289","DOIUrl":"10.1016/j.mne.2024.100289","url":null,"abstract":"<div><div>Photovoltaic retinal implants are emerging as a promising technological solution for restoring vision for patients suffering from retinal degenerative diseases such as retinitis pigmentosa and age-related macular degeneration. These prostheses contain arrays of miniaturized solar cells converting light into electrical output signals, which subsequently are employed for local activation of the intact neuroretina via microelectrodes. Leveraging cutting-edge microfabrication techniques, photovoltaic retinal implants are compact and provide a high density of solar cell pixels. This potentially increases the resolution of the artificial vision and the field of view and lowers the threshold for stimulation of retinal neurons. The introduction of flexible substrates and the integration of 3D electrodes has greatly improved the connection with retinal neurons, optimizing the spatial resolution and potentially lowering the stimulation threshold. This review explores the latest developments in photovoltaic retinal prostheses, highlighting key aspects of their design, fabrication and performance. This field of research is still in its early stage and particular emphasis is laid on promising future research directions including miniaturization of pixels, incorporation of organic flexible semiconductors and first studies considering 3D stimulating electrode structures. Despite the significant progress made, there are still substantial challenges to overcome, such as ensuring long-term biocompatibility and validation of the novel concepts in clinical trials. Ongoing interdisciplinary research and development are essential for moving these promising technologies from the lab to real-world clinical applications, ultimately enhancing vision restoration. This review aims to provide a comprehensive overview of the current state of photovoltaic retinal implants and pinpoints critical areas for future research to further advance this transformative technology.</div></div>","PeriodicalId":37111,"journal":{"name":"Micro and Nano Engineering","volume":"25 ","pages":"Article 100289"},"PeriodicalIF":2.8,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced plasma etching using nonlinear parameter evolution","authors":"Arjun Moothedath,&nbsp;Zhong Ren","doi":"10.1016/j.mne.2024.100288","DOIUrl":"10.1016/j.mne.2024.100288","url":null,"abstract":"<div><div>This study explores the development and characterization of plasma etching for sub-micron features using a nonlinear evolution of parameter in a three-step cyclic Bosch process. Comparing this nonlinear approach with traditional linear parameter evolution, we aimed to address issues such as bowing at the top of the features and narrowing at the bottom. Constant parameter etching produced tapered profiles, undercutting, and non-uniform scallops due to particle deflection. Linear parameter evolution partially mitigated these problems by balancing etch and deposition cycles and gradually increasing radio frequency power, achieving high selectivity to the photoresist. One nonlinear exponential evolution method resulted in a higher etch rate but caused slight damage to the top-side wall, while the etch depth was reduced. The other nonlinear method balanced the etch and deposition steps more effectively, achieving a comparable etch rate and selectivity to the linear method. Further optimization of this second method led to improved vertical profiles and controlled scallops, achieving greater depth, smoother sidewalls, and higher etch rates. This optimized technique successfully fabricated high aspect ratio periodic sub-micron structures with excellent uniformity across the wafer, demonstrating its potential for achieving even higher aspect ratios with thicker masks.</div></div>","PeriodicalId":37111,"journal":{"name":"Micro and Nano Engineering","volume":"25 ","pages":"Article 100288"},"PeriodicalIF":2.8,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Low-frequency electromagnetic harvester for wind turbine vibrations","authors":"Carlos Castellano-Aldave ,&nbsp;Aitor Plaza ,&nbsp;Xabier Iriarte ,&nbsp;Alfonso Carlosena","doi":"10.1016/j.mne.2024.100287","DOIUrl":"10.1016/j.mne.2024.100287","url":null,"abstract":"<div><p>In this paper we describe and fully characterize a novel vibration harvester intended to harness energy from the vibration of a wind turbine (WT), to potentially supply power to sensing nodes oriented to structural health monitoring (SHM). The harvester is based on electromagnetic conversion (EM) and can work with vibrations of ultra-low frequencies in any direction of a plane. The harvester bases on a first prototype already disclosed by the authors, but in this paper, we develop an accurate model parameterized by a combination of physical parameters and others related to the geometry of the device. The model allows predicting not only the power generation capabilities, but also the kinematic behaviour of the harvester. Model parameters are estimated by an identification procedure and validated experimentally. Last, the harvester is tested in real conditions on a wind turbine.</p></div>","PeriodicalId":37111,"journal":{"name":"Micro and Nano Engineering","volume":"25 ","pages":"Article 100287"},"PeriodicalIF":2.8,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2590007224000509/pdfft?md5=2b7b2a9954f6e29b0ae7cf9707532bc9&pid=1-s2.0-S2590007224000509-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142232865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From ghost to state-of-the-art process corrections – PEC enabled e-beam nanofabrication","authors":"Ulrich Hofmann,&nbsp;Nezih Ünal,&nbsp;Jan Klikovits","doi":"10.1016/j.mne.2024.100286","DOIUrl":"10.1016/j.mne.2024.100286","url":null,"abstract":"","PeriodicalId":37111,"journal":{"name":"Micro and Nano Engineering","volume":"25 ","pages":"Article 100286"},"PeriodicalIF":2.8,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2590007224000492/pdfft?md5=f62ae4e676dd49bc44a517f03b915f2a&pid=1-s2.0-S2590007224000492-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142229886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Single cell separation in microplates through micro patterning of “clickable” hydrogels","authors":"Alexander J. Straub ,&nbsp;Frank D. Scherag ,&nbsp;Mark-Steven Steiner ,&nbsp;Thomas Brandstetter ,&nbsp;Jürgen Rühe","doi":"10.1016/j.mne.2024.100285","DOIUrl":"10.1016/j.mne.2024.100285","url":null,"abstract":"<div><p>In this study, we report a novel approach for separating microspheres or cells on microstructured surfaces. These structures consist of μ-structured hydrogel coatings fabricated by photolithography on the bottoms of standard plastic microplate wells. The process is based on the deposition and subsequent irradiation of copolymers containing a hydrophilic main component and benzophenone moieties that can react with C, H groups during UV exposure through a photomask, a process known as “C,H insertion crosslinking” (CHic). The photolithographic process is used to generate an egg-box-like topography of the coating. Gravity, Brownian motion, and physical surface interactions drive particles or cells pipetted onto the surfaces to distinct locations on this topography so that after a short time these locations contain only one single particles or cells. We show that the presented technique enables the separation of thousands of objects as different as polymer microparticles or biological cells by simply adding a suspension to the coated wells of the microplate and wait for a short time (a few minutes). This strategy is quite general and not specific to a certain type of cell or microparticle and thus allow effortless separation of particles or cells.</p></div>","PeriodicalId":37111,"journal":{"name":"Micro and Nano Engineering","volume":"25 ","pages":"Article 100285"},"PeriodicalIF":2.8,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2590007224000480/pdfft?md5=82c83607116a2e2bcbb15cedee173954&pid=1-s2.0-S2590007224000480-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Removable support beams to improve the printing outcome of 2-photon-polymerized structures","authors":"Wiebke Gehlken ,&nbsp;Sina Reede ,&nbsp;Michael J. Vellekoop","doi":"10.1016/j.mne.2024.100283","DOIUrl":"10.1016/j.mne.2024.100283","url":null,"abstract":"<div><p>Using direct-laser writing, 3D microstructures of almost every shape can be fabricated. However, using liquid photoresists, the fabrication of free-floating structures is still challenging. To give stability to those structures during the printing process, support beams can be implemented which are usually not needed for direct-laser writing. With that, free-floating elements can be fixed and are not distorted due to unwanted movement during fabrication. In this work, the design, realization and characterization of support beams for the printing outcome of 2-photon polymerization processes is examined. The support beams described here connect the static and the rotating part of flap-like structures. Experimental results show that two thin cone-shaped support beams are sufficient to stabilize the flaps (typical size <span><math><mn>20</mn><mo>×</mo><mn>50</mn><mspace></mspace><mi>μ</mi><msup><mi>m</mi><mn>2</mn></msup></math></span>) so that they are not distorted during printing. After finishing the writing process, the support beams can be broken with a gentle nitrogen stream and the structures move freely. Structures like these can for example be implemented in microfluidic channels to work as flow direction pointers or self-closing cell traps.</p></div>","PeriodicalId":37111,"journal":{"name":"Micro and Nano Engineering","volume":"24 ","pages":"Article 100283"},"PeriodicalIF":2.8,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2590007224000467/pdfft?md5=3ace89fb3eb57c8c72b28de638ded657&pid=1-s2.0-S2590007224000467-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142130226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of highly sensitive vibration states of nanomechanical resonators in liquid using a convolutional neural network","authors":"Kazuki Bessho,&nbsp;Shin’ichi Warisawa,&nbsp;Reo Kometani","doi":"10.1016/j.mne.2024.100282","DOIUrl":"10.1016/j.mne.2024.100282","url":null,"abstract":"<div><p>Nanomechanical resonators can detect various small physical quantities with high sensitivity using changes in resonant properties. However, viscous damping in liquids significantly reduces the measurement sensitivity. This study proposes convolutional neural network (CNN) vibration spectrum analysis to evaluate the highly sensitive vibration states of nanomechanical resonators, which are useful for in-liquid measurements. This research was carried out through the measurement of acetone concentration. First, we compared the concentration classification ability between the proposed and conventional methods and determined that the proposed method of analyzing vibration spectral changes using the CNN model can provide higher measurement sensitivity than the conventional measurement method of observing resonance properties changes and comparing the values for each measurement condition. This result shows that CNN-based spectral analysis is effective for the vibration spectra of in-liquid measurements. Next, gradient-weighted class activation mapping (Grad-CAM) was applied to verify which frequency bands are important for concentration classification in CNN model decision-making. The vibration states in these frequency bands were analyzed in terms of oscillation modes. This analysis revealed significant oscillation modes of the nanomechanical resonator in the liquid environment. Notably, in addition to the resonance states utilized in the conventional method, several other oscillation modes were found to be significant for measurements. This finding suggests that these oscillation modes may be highly sensitive for measurements in liquid environments. Among these oscillation modes, the mode with very small amplitude is highly promising for achieving unprecedented levels of sensitivity in sensing technologies.</p></div>","PeriodicalId":37111,"journal":{"name":"Micro and Nano Engineering","volume":"24 ","pages":"Article 100282"},"PeriodicalIF":2.8,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2590007224000455/pdfft?md5=eb60cf33681506de331c155fcd8f695b&pid=1-s2.0-S2590007224000455-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142151745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dry etch performance of Novolak-based negative e-beam resist","authors":"Rahul Singh,&nbsp;Christian Vinther Bertelsen,&nbsp;Maria Dimaki,&nbsp;Winnie Edith Svendsen","doi":"10.1016/j.mne.2024.100284","DOIUrl":"10.1016/j.mne.2024.100284","url":null,"abstract":"<div><p>Electron beam lithography (EBL) is pivotal for micro- and nanoscale fabrication, offering sub-micron precision. This study explores the utilization of the Novolac-based negative resist AR-N 7520 for EBL and its potential as an etch mask for reactive ion etching (RIE) of silicon. Recent comparisons of negative EBL resists have revealed promising results for AR-N 7520 in terms of resolution and adaptability with other lithography techniques. In this article, we conduct an exploration of patterning of AR-N 7520 (new) for EBL, addressing key parameters in achieving optimal patterning fidelity. Furthermore, we investigate its compatibility with RIE processes, aiming to provide insights into its effectiveness as an etch mask for creating sub-micron silicon structures. Experimental results show that optimal e-beam dose with 100 kV exposure is 300–350 μC/cm². Selectivity of around 9:1 can be achieved by optimizing etching parameters for a continuous etch and higher than 14:1 for a cyclic etch process.</p></div>","PeriodicalId":37111,"journal":{"name":"Micro and Nano Engineering","volume":"25 ","pages":"Article 100284"},"PeriodicalIF":2.8,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2590007224000479/pdfft?md5=1916c605ea23c988a5ccc6c279b435e4&pid=1-s2.0-S2590007224000479-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142158141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lithographic resists as amazing compact imaging systems – A review","authors":"Uzodinma Okoroanyanwu","doi":"10.1016/j.mne.2024.100280","DOIUrl":"10.1016/j.mne.2024.100280","url":null,"abstract":"<div><p>Considering the goal of lithography under its most general aspect – that is, transferring and recording mask or template information in the form of contrast between the imaged and non-imaged areas of a resist film coated on a flat surface – three lithographic resist imaging mechanisms can be recognized. Depending on the nature of the resist film, this contrast may be based on intrinsic or photo- or radiation-induced differential solubility between the imaged and non-imaged part of the resist film in fine art lithography, photolithography, and radiation lithography, respectively, or pressure driven flow and confinement of resist in imprint lithography, or thermodynamically driven phase separation of resist constituents in directed self-assembly lithography. This contrast forms the basis of the printed image and ultimately derives from the forces that underlie the old chemist's rule: “Oil and water do not mix.” Crucially, to create this contrast, the resist film must transform a two-dimensional image of the mask or template into a three-dimensional relief image on the substrate in a process that is highly non-linear. By creating the contrast in this manner, the resist film serves as a compact imaging system that senses, records, stores, and displays the mask image. Additionally, the resist film must maintain its structural and mechanical integrity to “resist” and withstand the harshness of other post-imaging processes such as etching, ion implantation, electroplating, etc. Following all necessary post-imaging processes, the resist film must be stripped or be left and incorporated into the final device. A versatile material that serves a multiplicity of functions and is operational in many dimensions is not only amazing but also forms the irreducible essence of lithography. By drawing on fundamental, theoretical, and experimental studies of molecular processes involved in lithographic resist imaging, this review paper explains how the resist film performs the above essential functions.</p></div>","PeriodicalId":37111,"journal":{"name":"Micro and Nano Engineering","volume":"24 ","pages":"Article 100280"},"PeriodicalIF":2.8,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2590007224000431/pdfft?md5=64a88eb83a6bf8e1b3f71c8570b31d75&pid=1-s2.0-S2590007224000431-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141992928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}