Μm Side Research Articles

Micron-scale topographies affect phagocytosis of bacterial cells on polydimethylsiloxane surfaces

Many medical devices implanted in patients to mitigate diseases and medical conditions have different types of topographic features. While appropriate textures can promote the integration of host cells and reduce scar tissue formation, some textured implants with inappropriate topographies have been associated with inflammation, bacterial colonization, or even malignant complications. To better understand how surface topography affects host immune response to colonizing bacteria, a protocol was developed to investigate phagocytosis of bacterial cells attached on polydimethylsiloxane (PDMS) surfaces with different square-shaped recessive patterns. The interaction between activated RAW 264.7 macrophages and Escherichia coli in recessive wells was visualized in 3D using multiple fluorescent markers. The results revealed that there is a threshold dimension of topography, below which phagocytosis of attached bacterial cells is significantly impeded. Specifically, under our experimental condition, up to 100-fold reduction in phagocytosis was observed in square-shaped patterns with 5 µm side length and 10 µm depth compared to the flat control and patterns with 10 µm or longer side length. The spacing between wells also showed significant effects; e.g., phagocytosis in the wells further decreased when spacing increased to 50 µm. These results are helpful for understanding how undesired topographies may contribute to bacterial colonization and thus infection and other associated complications. Statement of significanceSurface topography plays an important role in bacteria-material infections and thus the safety of implantable medical devices. Undesired topographic features can cause biofilm formation and related complications. However, how surface topography affects the capability of host immune cells to clear colonizing bacteria is not well understood. In this study, the interaction between macrophage RAW264.7 and colonizing E. coli cells on polydimethylsiloxane (PDMS) with recessive features is investigated. It was discovered that the size of recessive features and the spacing between these features have significant effects on phagocytosis of bacteria by macrophages. These new results are helpful for understanding the complex interaction among host cells, bacteria, and implanted biomaterials, which will help guide the rational design of safer medical devices.

Efficacy of Biphasic Calcium Phosphate Ceramic With a Needle-Shaped Surface Topography Versus Autograft in Instrumented Posterolateral Spinal Fusion.

A multicenter randomized controlled noninferiority trial with intrapatient comparisons. The aim of this study was to determine noninferiority of a slowly resorbable biphasic calcium phosphate with submicron microporosity (BCP<μm, MagnetOs Granules) as an alternative for autograft in instrumented posterolateral fusion (PLF). Successful spinal fusion with a solid bone bridge between the vertebrae is traditionally achieved by grafting with autologous iliac bone. However, the disadvantages of autografts and unsatisfactory fusion rates have prompted the exploration of alternatives, including ceramics. Nevertheless, clinical evidence for the standalone use of these materials is limited. Adults indicated for instrumented PLF (1 to 6 levels) were enrolled at 5 participating centers. After bilateral instrumentation and fusion-bed preparation, the randomized allocation side (left or right) was disclosed. Per segment 10 cc of BCP<μm granules (1 to 2mm) were placed in the posterolateral gutter on one side and 10 cc autograft on the contralateral side. Fusion was systematically scored on 1-year follow-up CT scans. The study was powered to detect >15% inferiority with binomial paired comparisons of the fusion performance score per treatment side. Of the 100 patients (57 ± 12.9 y, 62% female), 91 subjects and 128 segments were analyzed. The overall posterolateral fusion rate per segment (left and/or right) was 83%. For the BCP<μm side only the fusion rate was 79% versus 47% for the autograft side (difference of 32 percentage points, 95% CI, 23-41). Analysis of the primary outcome confirmed the noninferiority of BCP<μm with an absolute difference in paired proportions of 39.6% (95% CI, 26.8-51.2; p < 0.001). This clinical trial demonstrates noninferiority and indicates superiority of MagnetOs Granules as a standalone ceramic when compared to autograft for posterolateral spinal fusion. These results challange the belief that autologous bone is the most optimal graft material.

Reinforcement induced microcracking during the conversion of polymer-derived ceramics

This study investigates the role of discontinuous reinforcement on the microcracking of a preceramic polymer matrix during polymer to ceramic conversion. The material system comprised a carbosilane-based, preceramic polymer reinforced with mullite particles. The preceramic resin slurry was formulated for photopolymerization on a digital light projection 3D printer. Micro X-ray computed tomography, using a synchrotron light source, monitored a printed composite part during pyrolysis. The conversion of the carbosilane matrix into Si(O)C generated microcracks in the matrix that radially extended from particles. The likelihood of microcrack formation positively correlated with particle size. The largest particles (>104 µm3 volume or >60 µm side length) always abutted microcracks, while the matrix surrounding smaller particles (<5 µm) was free of microcracks. Numerical calculations showed the particles resist the shrinking matrix during its conversion. This created tensile stresses within the matrix. The driving force for microcrack growth was also analyzed with regard to the influence of matrix material parameters, particle form-factor and crack length. These results reveal the need to consider the form factor of discontinuous reinforcements, with regard to the material properties of the polymer-derived ceramic, in order to reduce or eliminate defects in the final part.

407 Results of Biphasic Calcium Phosphate Bone Graft With Submicron-Sized Needle-Shaped Surface Topography as Standalone Alternative to Autograft Are Favorable in a Prospective, Multi-center, Randomized, Intra-patient Controlled Trial

INTRODUCTION: Pseudoarthrosis after spinal fusion is an important complication leading to revision spine surgeries. Iliac Crest Bone Graft is considered the gold standard, but with limited availability and associated co-morbidities, spine surgeons often utilize alternative bone grafts. METHODS: Adult patients indicated for instrumented PLF of one to six levels from T10-S2 were enrolled at five participating centers. After preparation of the bone bed, one side was grafted with 10 cc of autograft per level containing a minimum of 50% iliac crest bone. The other side was grafted with 10 cc of BCP &lt; µm granules standalone. In total, 71 levels were treated. Prospective follow-up included a fine-cut (&lt;1 mm) Computerized Tomography (CT) at one year. Fusion was systematically scored as fused or not fused per level per side by two spine surgeons blinded for the procedure. RESULTS: The first fifty patients enrolled are included in this analysis. Average age was 57 years old, with 60% female and 40% male. The diagnoses included deformity (56%), structural instability (28%), and instability from decompression (20%). The fusion rate determined by fine-cut CT for BCP &lt; μm was 76.1% (54/71 levels), which compared favorably to the autograft fusion rate of 43.7% (31/71 levels). Fusion of the BCP &lt; μm side was not contingent upon fusion of the autograft side, as 36.6% (26/71) of levels fused on the BCP &lt; μm side but did not fuse on the autograft side. Binomial modeling revealed that the odds of fusion of BCP &lt; μm was 2.54 times higher than that of autograft. CONCLUSIONS: These data, aiming to determine non-inferiority of standalone BCP &lt; μm as compared to autograft for PLF, are promising. Ongoing studies with additional patients are forthcoming.

Levofloxacin reposition-based design: synthesis, biological evaluation of new levofloxacin derivatives targeting topoisomerase II beta polymerase as promising anticancer agents, molecular docking, and physicochemical characterization.

Repositioning of already approved medications through repurposing or re-profiling for new medical uses after certain structural modifications is a novel approach in drug discovery. Fluoroquinolone antibiotics are one of the cardinal agents investigated for potential anticancer activities. In this work, levofloxacin was repositioned for anticancer activities. A series of levofloxacin-based compounds were designed and synthesized through the derivatization of levofloxacin's carboxylic acid functionality. The newly synthesized compounds were screened for cytotoxic activities against breast, liver, and leukemia cancer cell lines. Their effect on normal cells was also investigated. The target compounds were evaluated for their proliferative inhibitory activity toward topoisomerase II beta polymerization. Compound 5 showed higher inhibitory activity against a breast cancer cell line (MCF-7) with IC50 = 1.4 μM and lesser side effects on a normal breast cell line (MCF-10a) with IC50 = 30.40 μM than reference drugs. The best activity against a liver cancer cell line (Hep3B) was exhibited by compounds 3c, 4b, 5, 7, 8, 13a and 13c with IC50 values ranging from 0.43 to 8.79 μM. Regarding the effect of compounds 5 and 13a on a leukemia cancer cell line (L-SR), their IC50 values were 0.96 and 3.12 μM, respectively. Compounds 3c and 5 showed Topo2β inhibitory effects on Hep3B cells (81.33% and 83.73%, respectively), which was better than levofloxacin and etoposide as reference drugs. Cytometry cell cycle analysis revealed that compounds 3c and 5 arrested the cell cycle at the S phase (37.56% and 39.09%, respectively). Compounds 3c and 5 exhibited an elevation in active caspase-3 levels by 4.9 and 4.5 folds, respectively. Molecular modeling simulation of compounds 3c and 5 demonstrated energy scores (-29.77 and -20.46 kcal mol-1, respectively) more than those of the reference drugs as they interact with the most essential amino acids required for good affinity towards human topoisomerase II beta enzyme (PDB ID: 3QX3). Physicochemical characteristics of the most promising cytotoxic compounds 3c and 5 were investigated and compared to etoposide and levofloxacin as reference drugs. However, they showed high gastrointestinal absorption and could not penetrate the blood-brain barrier.

The Combined Spectral Response of a MEMS Metamaterial Absorber for the Mid-IR and Its Sub-Wavelength Fabrication Residual Array of Holes.

Metasurface coatings on a free-standing SiN thin film membrane are fabricated on a Si substrate using masked lithography and CMOS-compatible surface micromachining. The result is a band-limited absorber for the mid-IR, which is part of a microstructure that is attached to the substrate by long and slender suspension beams to provide thermal isolation. As a residual of the fabrication, the regular pattern of sub-wavelength unit cells of 2.6 μm side length, which defines the metasurface, is interrupted by an equally regular array of sub-wavelength holes of 1-2 μm diameter and at 7.8-15.6 μm of pitch. This array of holes is essential for enabling access of the etchant and attack of the underlying layer during fabrication, which ultimately results in the sacrificial release of the membrane from the underlying substrate. As the plasmonic responses of the two patterns interfere, a maximum is imposed on the hole diameter and a minimum on the hole-to-hole pitch. However, the hole diameter should be sufficiently large to allow access of the etchant, while the maximum spacing between holes is set by the limited selectivity of the different materials to the etchant during sacrificial release. The effect of the parasitic hole pattern on the spectral absorption of a metasurface design is analyzed by simulations of the responses of combined holes-metasurface structures. Arrays of 300 × 180 μm2 Al-Al2O3-Al MIM structures are mask-fabricated on suspended SiN beams. The results show that the effect of the array of holes can be disregarded for a hole-to-hole pitch larger than 6 times the side length of the metamaterial until cell, while the diameter of the hole should remain smaller than about 1.5 μm, and their alignment is critical.

Electrically Driven Sub-Micrometer Light-Emitting Diode Arrays Using Maskless and Etching-Free Pixelation.

For decades, group-III-nitride-based light-emitting diodes (LEDs) havebeen regarded as a light emitting source for future displays by virtue of their novel properties such as high efficiency, brightness, and stability. Nevertheless, realization of high pixel density displays is still challenging due to limitations of pixelation methods. Here, a maskless and etching-free micro-LED (µLED) pixelation method is developed via tailored He focused ion beam (FIB) irradiation technique, and electrically driven sub-micrometer-scale µLED pixel arrays are demonstrated. It is confirmed that optical quenching and electrical isolation effects are simultaneously induced at a certain ion dose (≈1014 ions cm-2 ) without surface damage. Furthermore, highly efficient µLED pixel arrays at sub-micrometer scale (square pixel, 0.5µm side length) are fabricated. Their pixelation and brightness are verified by various optical measurements such as cathodo-, photo-, and electroluminescence. It is expected that the FIB-induced optical quenching and electrical isolation method can pioneer a new defect engineering technology not only for µLED fabrication, but also for sub-micrometer-scale optoelectronic devices.

Synergetic effects of biomimetic microtexture with multi-solid lubricants to improve tribological properties of AISI 4140 steel

Inspired by the ability of tree frog toes to regulate body fluids, this control mechanism is applied to the tooth surface of slewing bearing (AISI 4140 steel (AS)) by adopting the regular hexagonal microtexture. SnAgCu-TiC (SACT) lubricants are filled in the microtextures. Results of two-factor analysis of variance show that there is a significant interaction between the microtexture and lubricants. When the microtextures with 1000 µm side are filled with SnAgCu-4 wt% nano-TiC (AS-SACT410), coefficient of friction (COF) of sample is the lowest. Compared with AS (0.437), COF of AS-SACT410 is reduced to 0.085, decreased by 80.55%. Macroscopic anti-friction originates because SnAgCu wraps around nano-TiC to form tribofilms containing submicron rollers, achieving substantially reduced COF.

Controlling Metal Halide Perovskite Crystal Growth via Microcontact Printed Hydrophobic‐Hydrophilic Templates

AbstractHerein, a simple, low‐cost, solution‐processed, and parallel fabrication method to form metal halide perovskite (MHP) poly and single‐crystalline films confined in ordered micrometer‐sized domains is reported. A cross‐linked polydimethylsiloxane (PDMS) stamp featuring 25 µm side squares is used to pattern their substrates. The substrate is microcontact printed on the PDMS inked with self‐assembled monolayers (SAMs) of alkanethiol to form a molecular template, resulting in hydrophilic (gold) and hydrophobic (alkanethiol) domains. The subsequent deposition of lead bromide (PbBr2) and methylammonium bromide (MABr) precursor solutions on the pre‐patterned substrate resulted in poly and single‐crystalline films of methylammonium lead bromide (MAPbBr3) confined to the hydrophilic domains. Two deposition methods: drop‐casting and two‐step spin‐coating are systematically investigated to find well confined and large‐sized single‐crystal MAPbBr3. Casting proves to be more effective than two‐step spin‐coating to achieve better confinement of MAPbBr3. The patterning process is monitored in dependence of the a) deposition methods used to b) precisely control the MAPbBr3 crystal growth in a pre‐defined site which leads to c) grow poly and single‐crystals in a periodic arrangement. Their nondestructive and less energy processable fabrication method will have its own contribution in transferring patterns to desired substrates that enables them to fabricate different types of MHP optoelectronic devices and integrated electronic systems with more complex architectures.

Laser Micro Polishing of Tool Steel 1.2379 (AISI D2): Influence of Intensity Distribution, Laser Beam Size, and Fluence on Surface Roughness and Area Rate

Within the scope of this study, basic research was carried out on laser micro polishing of the tool steel 1.2379 (AISI D2) using a square, top-hat shaped intensity distribution. The influence of three different quadratic laser beam sizes (100 µm, 200 µm, 400 µm side length) and fluences up to 12 J/cm2 on the resulting surface topography and roughness were investigated. Surface topography was analyzed by microscopy, white light interferometry, spectral roughness analysis, and 1D fast Fourier transformation. Scanning electron microscopy and electrical discharge analyses indicate that chromium carbides are the source of undesired surface features such as craters and dimples, which were generated inherently to the remelting process. Particularly for high laser fluences, a noticeable stripe structure was observed, which is typically a characteristic of a continuous remelting process. Although the micro-roughness was significantly reduced, often, the macro-roughness was increased. The results show that smaller laser polishing fluences are required for larger laser beam dimensions. Additionally, the same or even a lower surface roughness and less undesired surface features were created for larger laser beam dimensions. This shows a potential path for industrial applications of laser micro polishing, where area rates of up to several m2/min might be achievable with commercially available laser beam sources.

Study on surface texture patterns for improving tribological performance of bioimplants

A new surface texturing design was proposed for improving the tribological performance of bioimplants. Theoretical analysis was conducted to reveal the positive impact of round corner patterns. Experimental results indicated that round corner would significantly reduce the chance of interlocking phenomenon. Orthogonal experiments suggest that triangle pattern with 200 μm side length, 8–10 μm depth, 10% area density and square-distribution mode turns to be most effective in improving tribological performance of textured bioimplants, showing a 50% reduction in friction coefficient and 44.9% reduction in wear rate than that of polished samples. Working mechanisms of surface texturing in bioimplants were also comprehensively studied. It was confirmed that the extra lifting pressure provided by hydrodynamic effect was less than 1% of the ambient pressure. Further investigations proved that the negligible role of hydrodynamic pressure in the textured bioimplants was due to the low viscosity and slow sliding speed. On the other hand, the capacity to trap particles and second lubrication effect were found to be the main working mechanisms. • Interlocking effect could be the failure mechanism for some patten designs in bioimplants. • Only the patterns with round-corner should be adopted in the bioimplants. • Area density is the most influential pattern parameter while the distribution mode is the least one. • Capacity to trap particles and second lubrication effect are the main working mechanisms for textured bioimplants.

Gradient 3D Printed PLA Scaffolds on Biomedical Titanium: Mechanical Evaluation and Biocompatibility.

The goal of the present investigation was to find a solution to crucial engineering aspects related to the elaboration of multi-layered tissue-biomimicking composites. 3D printing technology was used to manufacture single-layered and gradient multi-layered 3D porous scaffolds made of poly-lactic acid (PLA). The scaffolds manufacturing process was optimized after adjusting key printing parameters. The scaffolds with 60 μm side length (square-shaped pores) showed increased stiffness values comparing to the other specimens. A silicone adhesive has been further used to join biomedical titanium plates, and the PLA scaffolds; in addition, titania nanotubes (TNTs were produced on the titanium for improved adhesion. The titanium-PLA scaffold single lap joints were evaluated in micro-tensile testing. The electrochemical processing of the titanium surface resulted in a 248% increase of the ultimate strength in the overlap area for dry specimens and 40% increase for specimens immersed in simulated body fluid. Finally, the biocompatibility of the produced scaffolds was evaluated with primary cell populations obtained after isolation from bone residual tissue. The manufactured scaffolds present promising features for applications in orthopedic implantology and are worth further.

Ultra-low power MEMS micro-heater device

In this paper, we propose a simple design for the heating device with ultra-low power consumption. The device is composed of a micro heater made of Nichrome (20/80) alloy, designed in simple meander shape covering the total surface of S = (1.25 × 104) × (102) µm2. Deposited in thin films with a thickness of 1 µm on square silicon membrane of 14 × 102 µm side and 10 µm of thickness. We used the COMSOL Multiphysics 4.3 a tool for simulation. We achieved a maximum temperature of 900 K by applying 1.5 V of voltage. For gas sensing, the temperature of 707 K is generated at 1.25 V of voltage while the power consumption is 1.25 µW. The maximum relative stress is 3.5 109 N/m2 at 1.5 V. However, at 1.25 V we have less stress of 109 N/m2 and 9.107 × 10− 3 N/m2 for the interface thermo-mechanical strain resulting in good reliability for the device. Finally, the total displacement for the membrane is 50 µm as a maximum when 1.5 V is applied and 35 µm at 1.25 V. this device is perfectly adapted for mobile application as gas sensing and IoT systems.

Parametric Study on In Situ Laser Powder Bed Fusion of Mo(Si1-x,Alx)2.

Mo(Si1−x,Alx)2 composites were produced by a pulsed laser reactive selective laser melting of MoSi2 and 30 wt.% AlSi10Mg powder mixture. The parametric study, altering the laser power between 100 and 300 W and scan speed between 400 and 1500 mm·s−1, has been conducted to estimate the effect of processing parameters on printed coupon samples’ quality. It was shown that samples prepared at 150–200 W laser power and 400–500 mm·s−1 scan speed, as well as 250 W laser power along with 700 mm·s−1 scan speed, provide a relatively good surface finish with 6.5 ± 0.5 µm–10.3 ± 0.8 µm roughness at the top of coupons, and 9.3 ± 0.7 µm–13.2 ± 1.1 µm side surface roughness in addition to a remarkable chemical and microstructural homogeneity. An increase in the laser power and a decrease in the scan speed led to an apparent improvement in the densification behavior resulting in printed coupons of up to 99.8% relative density and hardness of ~600 HV1 or ~560 HV5. The printed parts are composed of epitaxially grown columnar dendritic melt pool cores and coarser dendrites beyond the morphological transition zone in overlapped regions. An increase in the scanning speed at a fixed laser power and a decrease in the power at a fixed scan speed prohibited the complete single displacement reaction between MoSi2 and aluminum, leading to unreacted MoSi2 and Al lean hexagonal Mo(Si1−x,Alx)2 phase.

Macroporous silicon coated with M/TiO2 (M=Au,Pt) as a highly efficient photoreactor for hydrogen production

Macroporous silicon disks containing ordered channels of 2 μm side and 0.2 mm length (9 × 106 channels cm−2) have been functionalized with a thin layer of Au/TiO2 and Pt/TiO2 photocatalysts and tested in the photoproduction of hydrogen using UV light from water-ethanol mixtures in gas phase. An outstanding hydrogen production rate of 212 μmol h−1 cm−3reactor is demonstrated, which is three orders of magnitude higher than those achieved in conventional photoreactors. According to the simulation results, the fabulous hydrogen production rates obtained with the macroporous silicon photocatalytic structures are ascribed to an extraordinary high specific surface area per volume unit and to an enhanced light exploitation. This new microphotoreactor concept could boost the production of solar hydrogen for on-site and portable applications.

Voltage Dependent Anion Channels Regulate Proliferation of Cancer Stem Cells

Cancer stem cells (CSCs) are associated with tumor progression and resistance to chemotherapy. Oxidative phosphorylation and aerobic glycolysis in CSCs are dynamically regulated. Mitochondrial metabolism and membrane potential (ΔΨ) are contributed by the ingress of respiratory substrates, ADP and Pi into mitochondria through voltage-dependent anion channels 1/2/3 (VDAC). We previously demonstrated that free tubulin closes VDAC and erastin antagonizes the tubulin inhibition of VDAC1/2 but not VDAC3. VDAC opening increases mitochondrial metabolism decreasing glycolysis and proliferation. Here, we hypothesized that different VDAC isoforms, by controlling oxidative metabolism, regulate proliferation of CSCs. CSCs from HepG2 and Huh7 human hepatocarcinoma and HCC4006 lung adenocarcinoma cells (spheres >50 µm diameter) were generated using ultra-low attachment plates (DMEM-F12 medium supplemented with B-27, EGF and bFGF). Markers of pluripotency were assessed by qPCR, western blotting and immunostaining. Spheres were counted using 50 µm side grid units. Tetramethylrhodamine methyl ester fluorescence to assess ΔΨ was determined both using a microplate reader and confocal fluorescence microscopy. The relative contribution of each VDAC isoform was similar in all CSCs and bulk cancer cells (CCs). By contrast, VDAC 2/3 mRNA levels were higher in CSCs compared to bulk HepG2, Huh7 and HCC4006 whereas VDAC1 was higher only in HepG2 and Huh7 CSCs. VDAC1 single knockdown in HepG2 and Huh7 CSCs decreased sphere formation by ∼30%. VDAC2 and VDAC3 single knockdown increased both the amount (∼18% and 102%, respectively) and the size of spheroids. VDAC1/2/3 single knockdown decreased ΔΨ. Erastin decreased sphere formation and promoted intra-sphere cell death in HepG2 and Huh7 CSCs. VDAC1/2 but not VDAC3 contribute to the maintenance and proliferation of CSCs. VDAC1/2 opening by erastin may decrease sphere formation and promote cell death by enhancing oxidative metabolism and decreasing glycolysis.

Dark Current Analysis of InAsSb-Based Hetero-$p{\text{-}}i{\text{-}}n$ Mid-Infrared Photodiode

We comprehensively study the characteristics of dark current for a p-i-n heterostructure photodiode. To reduce the dark current, a wide-bandgap layer (AlGaSb) and thin quaternary layers (AlInAsSb) are inserted in the heterostructure for blocking the dark carrier diffusion and limiting type-II transition at interface, respectively. The activation energy derived from measurement results indicates the positive (negative) correlation between the dominant dark current density and voltage bias (temperature). Whatever the voltage bias (temperature), this relationship always exists, indicating the high stability and reliability of our devices. Indeed, the measures taken for reducing dark current are confirmed to be effective as the dark current density for this photodiode is limited to a lower level. For the typical square mesa with 350 μm side length, at the bias of -0.4 V, the dark current density is 1.78 A/cm 2 for T=293 K, and reduces to 0.4 A/cm 2 for T=77 K, where the room-temperature value is lower than or comparable with that of the state-of-the-art mid-infrared photodetectors. A room-temperature detectivity of 8.3×10 8 cm·Hz 1/2 /W with a cut-off wavelength of 4 μm is demonstrated.

A 50 ps resolution monolithic active pixel sensor without internal gain in SiGe BiCMOS technology

A monolithic pixelated silicon detector designed for high time resolution has been produced in the SG13G2 130 nm SiGe BiCMOS technology of IHP. This proof-of-concept chip contains hexagonal pixels of 65 μm and 130 μm side. The SiGe front-end electronics implemented provides an equivalent noise charge of 90 and 160 e− for a pixel capacitance of 70 and 220 fF, respectively, and a total time walk of less than 1 ns. Lab measurements with a 90Sr source show a time resolution of the order of 50 ps. This result is competitive with silicon technologies that integrate an avalanche gain mechanism.

Micro Vacuum Chuck and Tensile Test System for Bio-Mechanical Evaluation of 3D Tissue Constructed of Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes (hiPS-CM).

In this report, we propose a micro vacuum chuck (MVC) which can connect three-dimensional (3D) tissues to a tensile test system by vacuum pressure. Because the MVC fixes the 3D tissue by vacuum pressure generated on multiple vacuum holes, it is expected that the MVC can fix 3D tissue to the system easily and mitigate the damage which can happen by handling during fixing. In order to decide optimum conditions for the size of the vacuum holes and the vacuum pressure, various sized vacuum holes and vacuum pressures were applied to a normal human cardiac fibroblast 3D tissue. From the results, we confirmed that a square shape with 100 µm sides was better for fixing the 3D tissue. Then we mounted our developed MVCs on a specially developed tensile test system and measured the bio-mechanical property (beating force) of cardiac 3D tissue which was constructed of human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CM); the 3D tissue had been assembled by the layer-by-layer (LbL) method. We measured the beating force of the cardiac 3D tissue and confirmed the measured force followed the Frank-Starling relationship. This indicates that the beating property of cardiac 3D tissue obtained by the LbL method was close to that of native cardiac tissue.

Demonstration of the CDMA-mode CAOS smart camera.

Demonstrated is the code division multiple access (CDMA)-mode coded access optical sensor (CAOS) smart camera suited for bright target scenarios. Deploying a silicon CMOS sensor and a silicon point detector within a digital micro-mirror device (DMD)-based spatially isolating hybrid camera design, this smart imager first engages the DMD starring mode with a controlled factor of 200 high optical attenuation of the scene irradiance to provide a classic unsaturated CMOS sensor-based image for target intelligence gathering. Next, this CMOS sensor provided image data is used to acquire a focused zone more robust un-attenuated true target image using the time-modulated CDMA-mode of the CAOS camera. Using four different bright light test target scenes, successfully demonstrated is a proof-of-concept visible band CAOS smart camera operating in the CDMA-mode using up-to 4096 bits length Walsh design CAOS pixel codes with a maximum 10 KHz code bit rate giving a 0.4096 seconds CAOS frame acquisition time. A 16-bit analog-to-digital converter (ADC) with time domain correlation digital signal processing (DSP) generates the CDMA-mode images with a 3600 CAOS pixel count and a best spatial resolution of one micro-mirror square pixel size of 13.68 μm side. The CDMA-mode of the CAOS smart camera is suited for applications where robust high dynamic range (DR) imaging is needed for un-attenuated un-spoiled bright light spectrally diverse targets.