Drop Placement Research Articles

Modeling and analysis of Double-Double composite structures integrating piezoelectric materials

Multifunctional materials and structures are increasingly important for innovative structural solutions. This work aims to model such structures constituted by Double-Double composites and piezoelectric materials. Besides the homogenization trend of these laminates as the number of the replicating sub-laminates grows, other features include simple ply drop placement, and card sliding to potentially save weight. To control the mechanical response, piezoelectrics along with several types of stacking were considered. The first-order shear deformation theory implemented via the finite element method was used to assess the model, and a set of verification and parametric studies was developed, resulting in a good performance confirmation.

Picoliter drop deposition of SnO2 nanoparticles onto microsensor platforms

Microhotplates produced by micromachining processes provide a robust substrate for miniaturized solid-state gas sensors; however, it can be challenging to locally deposit solution-suspended nanomaterials for sensing directly onto these small (≈ 100 µm), 3-dimensional platforms which are often configured in arrays to increase analytical capabilities. A picoliter drop-deposition technique based on inkjet printing is described here which has been used to achieve accurate, precise drop placement and reproducible film formation. Tin oxide nanoparticles, a well-established sensing material for use in gas sensor devices, were used to demonstrate the methodology. The nanoparticles were synthesized via a hydrothermal route to achieve crystalline materials with an average diameter of 5.5 nm. Tin oxide nanoparticle-laden suspensions were then formulated to reduce agglomeration, enable consistent first-drop formation, and prevent dispenser clogging. A priming technique was developed to accurately and repeatably perform deposition of picoliter-range drops onto the microsensor platforms. The technique was employed with a dynamic drop placement procedure to yield formation of spatially registered mesoporous oxide films on individual microhotplates. Microsensors fabricated with the drop-deposited SnO2 nanoparticles showed sensitive and rapid gas-sensing responses to two reducing gases and one oxidizing gas when tested at concentrations within the range of (5 to 100) µmol/mol. The presented results indicate that the combination of pre-formed nanoparticles and picoliter drop deposition offers a versatile approach for reproducibly manufacturing gas microsensors, which can be adapted for a range of gas sensing materials and microscale platforms.

Novel and Efficient Methodology for Drop Placement Accuracy Testing of Robot-Guided Inkjet Printing onto 3D Objects

Robot-guided inkjet printing technology offers a new way for the digital and additive deposition of low-viscous inks to be made directly onto arbitrary surfaces and, thus, enables the production of individualized printed electronics on large-scale objects. When compared to conventional flatbed printing, the distance between the nozzle plate and the object’s surface varies and needs to be considered in order to match the accuracy requirements needed for the positioning of single drops. Knowledge about applicable distance limits and the influence of tunable print parameters is crucial for improving the print process and results. This study discusses the sources of errors in the inkjet printing process onto 3D objects and presents extensive results about position accuracy in relation to jetting distance for different parameter sets of functional inks, drop volumes, and piezo voltages. Additionally, an efficient novel method was applied to determine the drop position accuracy of inkjet droplets in relation to the jetting distance. The method relies on cylinder geometry for the object and an inkjet head that is guided by a six-axis robot manipulator along the cylinder’s axis. For the determination of drop placement accuracy, the position of single dots on the surface was compared to a model which considered the cylinder radii, drop velocity, and the movement speed of the guided inkjet printhead. The method and the extensive research results can be utilized for the prediction of achievable drop placement accuracy and the prior definition of distance limits.

Isotopic evaluation of in‐season Y Drop applications for corn production

AbstractA common strategy for improving fertilizer N uptake efficiency by corn (Zea mays L.) is to synchronize application with crop N demand during the growing season, which can be done using the Y Drop system recently developed for surface dribble placement. A 2‐yr field study was conducted using dual‐labeled urea‐ammonium nitrate (UAN) solution to compare fertilizer 15N uptake efficiency (F15NUE) for surface and subsurface sidedress applications to soils of contrasting fertility under either second‐year corn or a corn–soybean [Glycine max (L.) Merr.] rotation. Besides placement, treatments were designed to allow comparison of 15N uptake from UAN applications made at planting vs. at the V9 growth stage. The importance of soil N supply was demonstrated by estimates of N derived from fertilizer that ranged from 17 to 47% in total aboveground biomass and never exceeded N derived from soil. Of the fertilizer N recovered in the crop at harvest, the majority originated from the 15N applied at sidedressing rather than at planting. The range in F15NUE was from 12 to 42% (26% on average) for grain and from 14 to 51% (31% on average) for total aboveground biomass, the only significant difference occurring when the subsurface treatment outperformed Y Drop placement under conditions conducive to urea N loss through NH3 volatilization. Both methods of application offer the same fundamental advantage, in that fertilizer N is supplied during the period of maximal crop uptake.

Novel genetic algorithms for femtoliter jetting using multi-nozzle MEMS printheads (femtoliter jetting using MEMS printheads)

Piezoelectric inkjets have enabled highly precise, customized material deposition for the micro and nanofabrication industries. Inkjet performance relies on a delicate balance between hardware manufacturing precision and tolerancing, material rheology, and the associated actuation-waveform for drop ejection. For a multi-nozzle inkjet system, the important performance metrics include drop volume resolution, inter-nozzle drop volume variation, overall drop-placement accuracy, jetting frequency (related to throughput), and long-term reliability. Cutting-edge applications typically require minimizing drop volume to 1 pL or less; drop placement accuracy of <10 mm, 3-σ; maintaining high jetting frequency of >10 kHz; and achieving reliable long-term operation, e.g., >1 month of continuous operation without any faults. Here, we strive towards a global optimum in drop resolution while adhering to constraints related to placement accuracy and reliability, at a fixed jetting frequency of 14.2 kHz. Our approach is to explore novel genetic algorithms that generate highly complicated waveforms (>100 parameter waveforms) to achieve our global optimum goals. Our automated genetic algorithm (a) starts from rudimentary waveforms that are easily constructed based on empirical knowledge and manual tuning, and (b) systematically increases complexity to generate highly sophisticated waveforms with increasingly greater number of parameters, an approach that is unattainable through manual tuning processes. This approach was developed and implemented using a commercial MEMS-based Fujifilm Samba G3L piezo-inkjet system with 2048 sub-20μm nozzles, with an aqueous diethylene glycol-based ink supplied by Fujifilm. The genetic algorithm operated based on a variable-length chromosome which started with 10 parameter waveforms and evolved into waveforms defined by > 100 parameters, resulting in drop-volume resolution of <600 fL, and maintaining drop placement accuracy to within 10 μm, 3-σ with reliable jetting over at least 30 print fields with the same waveform, each field nominally composed of 340 drops. The best result presented yielded drops with an average volume of 568 fL, which exceeded the manufacturer's specification for drop volume of 2.4 pL by 4.23 times. In summary, we have developed a novel framework for machine-in-the-loop waveform optimization in multi-nozzle inkjet systems to achieve previously unattained drop resolution with high reliability and accuracy.

Comparison of the Usability of Eye Drop Aids and the Conventional Bottle.

(1) Background: Eye drops are the most common route of administration for ophthalmic medications. Administering drops can be a major hurdle for patients, potentially resulting in noncompliance and treatment failure. The purpose of this study is to compare the efficacy and safety of two different aids and the conventional bottle for eye drop instillation; (2) Methods: An interventional crossover study involving standard eye drop bottle, Opticare aid and Autodrop aid. The study included healthy subjects without a history of regular eye drop use; (3) Results: Twenty-six subjects were enrolled. Of those subjects, 96% and 92% were able to assemble the eye drop bottle into the Autodrop and the Opticare aids, respectively. Subjective assessment indicated that Autodrop was significantly easier to assemble than Opticare (95% CI: −1.6802 to −0.1659, p = 0.02). When using either aid, there was no contamination of the bottle tip, which occurred in 46% of subjects when no aid was used (p = 0.0005). Fewer drops were expelled when using the conventional bottle as compared to the aids (p = 0.05 compared to Autodrop, p = 0.1 compared to Opticare); (4) Conclusions: Autodrop and Opticare can assist patients with eye drop placement. These aids completely prevented bottle tip contamination, which was frequently observed when the conventional bottle was used alone.

Double–Double: New Family of Composite Laminates

A new family of composite laminates could revolutionize composite structures to be lighter, stronger, easier to understand and design, and faster and lower cost to manufacture. For the last 60 years, traditional quad laminates (quad) based on collections of 0, , 90 plies have controlled composite laminates. However, restriction to four specific angle orientations has unnecessarily limited design and production. The newly discovered laminate family, called double–double laminates (DD), based on two pairs of angle-plies, can redirect the trend instead toward simplicity and rationality. Advantages enabled by DD include homogenization, tapering to save weight, ply drop placement to improve quality, and card sliding to simplify ply stacking. A switch from quad to DD laminates can bring a renaissance to the composites industry for the production of better airplanes, cars, and other important engineering applications.

Transdermal anti-inflammatory therapy for aqueous deficiency.

Lacrimal gland inflammation has been identified as an important limitation on aqueous production and associated dry eye disease. Ocular surface inflammation in dry eye disease can be a downstream response to reduced quantities of warmer hyperosmotic aqueous being delivered from an inflamed lacrimal gland with high concentrations of inflammatory mediators. This review examines evidence which shows how topical applications of anti-inflammatory drugs have very limited access to the lacrimal gland and an associated limited capacity to increase aqueous flow by reducing inflammation in the main lacrimal gland. Using cyclosporine as an exemplar immunomodulatory drug, this review examines problems associated with the topical administration of all anti-inflammatory drugs in the treatment of dry eye disease. Limited access to the lacrimal gland for topical applications and their very short on-eye residence times are compared with the therapeutic potential of prolonged therapeutic episodes that could be achieved with transdermal applications of a drug to the skin at the site of the lacrimal gland. Poor access to the lacrimal gland for topically administered drugs is a major barrier to the treatment of aqueous deficiency. While topical inflammatory drug access to the ocular surface is direct, poor access to the lacrimal gland is partly due to drop placement being downstream to the flow of aqueous (Eye Vis 2020;7:1; Eye Vis 2019;6:1). This barrier is much greater according to the degree that reflex tear flow is stimulated by irritation associated with adverse drop temperature, and/or pH and/or tonicity for example.

A Randomized Controlled Clinical Trial to Compare Conventional Drug Instillation to A Device Dropper Method in Medical Treatment of Glaucoma

ABSTRACT Purpose To compare and analyze the performance of a device dropper (DD) over conventional drop instillation (CDI) method on ease of administration, compliance, patient satisfaction, and intraocular pressure (IOP) control in persons with glaucoma on ocular hypotensive medications. Methods We enrolled 72 individuals with primary open-angle glaucoma or ocular hypertension, on treatment with fixed combination (α agonist+β blocker) drugs for at least 6 months. These were randomized into two groups (36 in each arm). Group 1 administered the drug with a DD and Group 2 used CDI method. Recruited individuals were interviewed for subjective difficulties using a formatted questionnaire at first month follow-up and IOP change from baseline was evaluated. Results Baseline demographic and ocular characteristics were similar in both groups. 57.1% in the conventional instillation and none in the DD had reported difficulty in using the eye drops on follow-up visit. DD group had significantly less spillage and contamination of eye surface or dropper tips, required minimal assistance, accurately targeted on first drop placement directly into the eye compared to CDI group (p-value<0.001). Mean IOP was comparable between the two groups. Conclusion DD instillation method was observed to be easier to administer, more accurate in targeting the conjunctival cul-de-sac, reduced wastage with lesser contamination compared to the CDI technique. DDs may be expected to have better compliance and effectiveness in medical management of glaucoma.

Machine vision methodology for inkjet printing drop sequence generation and validation

Inkjet printing technology for printed microelectronics suffers from a number of non-idealities due to unwanted ink flow on the substrate. This can be mitigated and pattern fidelity can be improved by using an optimized drop placement sequence in contrast to the standard raster-scanning approach. However, it is challenging to auto-generate such printing sequences for complex printed patterns. Here, the generation and evaluation of the printing sequence are turned into a computer-vision problem. The desired printed pattern is taken as an input image and converted into a printing sequence using contour, symmetric, and matrix sequencing and corner compensation. After printing, pattern defects are detected by automated image processing to evaluate the printed pattern against the designed ground truth image and to determine the best possible algorithm for printing sequence generation for different pattern types. The machine vision-based experimental approach identifies the best solutions for solving the printing and defect optimization problem in terms of precision, recall, and accuracy. This methodology will enable the automated design of electronic circuits for applications such as wearable sensors, low-cost radio-frequency identification tags, or flexible displays.

36‐2: Invited Paper: The Latest Breakthrough of Printing Technology for Next Generation Premium TV

The ink jet printing RGB patterning technology (“Printing Technology”) for OLED TV application is gathering momentum toward commercialization. The main technical challenges of printing technology, are (1) to improve the OLED TV panel performance fabricated by printing technology, and (2) to establish manufacturable the G8.5/G11 MURA‐Free printing technology. Recently, the printing technology has made tremendous progress in terms of OLED material performance( life time, current efficiency, color gamut and driving voltage) including optimization of top emission device architecture and maturity of MURA‐Free ink‐jet printing technology ,such as high performance ink‐jet printing equipment equipped with excellent print‐head in terms of drop volume uniformity and drop placement accuracy, ink formulation for reliable jetting, hydrophobic bank material/design/process and unique vacuum dry &amp; bake process.TCL Group (Guangdong Juhua Printed Display Technology, TCL Corporate Research, TCL CSOT) has been developing the manufacturable printing technology for TV application and innovative flexible display technology since 2015. Based on development activities of 31” 4K OLED TV, 31” 4K H‐QLED TV(World 1st Demo at CES 2019), 31” FHD Flexible Printed OLED TV and 4.92” (403ppi) high resolution panel, the latest breakthrough of printing technology for next generation premium TV is discussed in details.

Improved Inkjet-Printed Pattern Fidelity: Suppressing Bulges by Segmented and Symmetric Drop Placement

Abstract Inkjet printing is a promising technique for printed micro-electronics due to low cost, customizability and compatibility with large-area, flexible substrates. However, printed line shapes can suffer from bulges at the start of lines and at corner points in 2D line patterns. The printed pattern can be multiple times wider than the designed linewidth. This can severely impact manufacturing accuracy and achievable circuit density. Bulging can be difficult to prevent without changing the ink-substrate-system, the drying conditions or the circuit design, all of which can be undesirable. Here, we demonstrate a novel printing methodology that solves this issue by changing the order in which drops are placed on the substrate. The pattern is split up into segments of three drops where the central drop is printed last. This symmetric printing prevents the unwanted ink flow that causes bulging. Larger bulge-free patterns are created by successively connecting segments. Line formation in both traditional linear printing and our novel segmented and symmetric printing was analyzed to understand and optimize results. The printing of X-, T-, and L-shapes is considerably improved compared with the traditional linear printing methodology.

Drops That Change Their Mind: Spontaneous Reversal from Spreading to Retraction.

A liquid drop may spread faster on surfaces when surfactants are added. Here we show that after some time the spreading in such systems can, under certain conditions, spontaneously reverse to retraction and the droplet pulls itself back, receding from areas it has just recently wetted, elevating its center of mass in a jerklike motion. The duration from drop placement to the onset of retraction ranges from hours to less than a second primarily as a function of surfactant concentration. When the retraction is asymmetric, it results in drop motion, and when it is symmetric, the mass of the drop collects itself on its spot. This phenomenon, which was predicted theoretically in 2014, is apparently a general one for drops with surfactants; however, other factors, such as evaporation and contamination, prevented its observance so far.

Characterization of thermal inkjet droplets jitter

Due to the randomness in the nucleation process of vapor bubbles and the instability of ink drop breakup in the thermal inkjet drop ejector, the drop velocity varies slightly from drop to drop, such a variation is called the jitter of the droplets. Droplet jitter causes variations in drop volume, satellite drop formation, and drop placement error on the receiving substrate, which limit the high accuracy printing application for thermal inkjet. Traditionally, a multiple-exposure method is used to photograph the droplets in flight, which is unable to measure jitters of every drop due to the low sampling rate. In this study, a laser-based high-speed flying drop measurement system is used to study the jitter. We tentatively propose a simple model to explain the cause of droplet jitter, which is related to the latency phenomenon, the randomness in droplet formation and the difference in droplets velocity. The jitter is recorded under different driving conditions and the distribution of jitter is analyzed. As a conclusion, the conditions for operation to achieve lower jitter are determined. Under certain driving conditions, the jitter can be reduced by 90%.

The Phenylephrine Test Revisited.

To characterize the phenylephrine test in ptotic patients to help clinicians perform the test more efficiently. Adults with involutional ptosis (n = 24, 30 eyes) were assessed with digital photographs for response to topical 2.5% phenylephrine drop instillation. Patient characteristics (age, gender, iris color, dermatochalasis, brow ptosis, and baseline marginal reflex distance-1 [MRD-1] height) were recorded. From the photographs, change in (MRD-1), presence of conjunctival blanching, pupillary dilation, and Hering effect were recorded at specified time intervals, 1 minute to 1 hour after drop placement. Correlations between patient characteristics and measured outcomes were evaluated using analysis of variance, Pearson coefficient, or chi-square tests. The authors found that 73% of eyes had eyelid elevation with phenylephrine. Of these, 50% reached maximal eyelid elevation by 5 minutes, and 86% by 10 minutes after drop placement, but 14% did not reach maximal MRD-1 until 30 minutes. There is a negative correlation between the maximum MRD-1 and the baseline MRD-1 eyelid height (r = -0.5330, p < 0.01). There is no significant relationship between time to pupillary dilation with either time to max eyelid elevation or max eyelid elevation. No patient characteristic studied affected the likelihood of eyelid response to phenylephrine or presence of Hering effect. Although most ptotic eyelids demonstrate a response to 2.5% phenylephrine within 10 minutes, there is a subset of patients that respond much later. More ptotic eyelids had greater eyelid elevation with phenylephrine. Pupillary dilation and conjunctival blanching are neither predictive of nor temporally associated with eyelid height elevation. The authors did not identify any patient factors (e.g., dermatochalasis, brow ptosis) that can predict the likelihood of response to phenylephrine.

Endophthalmitis Prophylaxis Using a Single Drop of Thermoresponsive Controlled-Release Microspheres Loaded with Moxifloxacin in a Rabbit Model.

PurposePostsurgical endophthalmitis is a sight-threatening problem. We introduce a simple approach by using a single application of thermoresponsive controlled-release microspheres, loaded with moxifloxacin, to prevent bacterial endophthalmitis in a rabbit endophthalmitis prevention model.MethodsWe separated 24 rabbits into 3 treatment groups in which topical drop treatment was placed onto the conjunctival cul-de-sac: (1) a single drop of controlled-release microspheres containing moxifloxacin, (2) a single drop of controlled-release microspheres without moxifloxacin, and (3) multiple topical treatment with moxifloxacin alone every 15 minutes for 1 hour. All rabbits were challenged, 1 hour after microspheres drop placement and immediately after the fifth topical dose of moxifloxacin, with anterior chamber injections of Staphylococcus aureus. Rabbits in the topical moxifloxacin group also were treated after challenge and four additional times over the next 24 hours. After 24 hours, the rabbits were clinically evaluated for endophthalmitis and the animals were euthanized to culture for intraocular S. aureus. The treatment groups were compared statistically for bacterial endophthalmitis.ResultsNo eyes had endophthalmitis, based on clinical presentation and/or positive culture, in the groups with controlled-release microspheres loaded with moxifloxacin (0/8, 0%) or multiple drops of topical moxifloxacin (0/8, 0%). In contrast, 8 of 8 eyes (100%; P = 0.0001), had endophthalmitis among eyes treated with controlled-release microspheres drops without moxifloxacin.ConclusionA single drop of controlled-release microspheres loaded with moxifloxacin was successful in preventing endophthalmitis. Further clinical studies will be required to confirm the full potential of controlled-release anti-infective loaded microspheres to prevent endophthalmitis.Translational RelevanceThis study presents a simple method of prophylaxis to prevent postsurgical endophthalmitis.

Influence of discrete drop locations on film thickness uniformity in UV- nanoimprint lithography

Multi-nozzle inkjetting is the material deposition approach for a variant of UV-nanoimprint lithography called Jet-and-Flash Imprint Lithography (J-FIL). J-FIL has several advantages with respect to addressing pattern density variations in the template as well as achieving low material waste when compared with spin-coating. In this work, the influence of discrete drop placement in J-FIL on residual layer thickness uniformity has been investigated with the help of a novel nonlinear lubrication theory model, which takes into account the compliant nature of the template in the presence of a moving contact line. This work is directed at thin residual layers (sub-20nm), where a correlation exists between minimum drop resolution, inkjet nozzle pitch and residual layer thickness uniformity. Numerical simulations reveal that the non-uniformity resulting from discrete drop placement can exceed desired process tolerances when low film thicknesses are desired with relatively larger drop volumes. The results have been verified experimentally to reveal the same trend. This work can be useful in determining the correlation of inkjet drop resolution with inkjet nozzle pitch to meet process tolerances in the J-FIL process.

A Study of the Association Between Patterns of Eye Drop Prescription and Medication Usage in Glaucoma Subjects

To investigate the association between patterns of eye drop prescription and medication usage in patients with glaucoma. Sixty-seven Japanese patients with glaucoma who were prescribed topical antiglaucoma medications including a prostaglandin analogue bilaterally for >6 months at Nayoro City General Hospital, Nayoro, Japan, were included in the study. A self-administered, 5-item patient questionnaire was administered to determine how patients routinely use medications, including the method of eye drop administration, number of eye drops per instillation, accuracy of eye drop placement, weekly frequency of eye drop application, and their awareness of local side effects. The number of prostaglandin analogue bottles prescribed monthly was compared in each factor. The mean patient age was 74.4±10.0 years (range, 52 to 95 y; 39 women, 28 men). The mean duration of glaucoma treatment was 4.2±3.2 years (range, 0.7 to 10.6 y). Patients who placed the eye drops outside the eye were prescribed significantly more bottles monthly (P=0.008). The other factors had no significant effect on the number of bottles prescribed monthly. Patients with glaucoma who used eye drops incorrectly were routinely prescribed additional bottles of eye drops. Ophthalmologists should determine whether patients who request an unusual number of eye drops are using the eye drops correctly.

Aerodynamic Effects in Industrial Inkjet Printing

The quality achieved by inkjet printing is limited by various factors, including the nozzle&#x2013;substrate throw distance, the substrate velocity, and the occurrence of satellite droplets. Under certain conditions, particularly for large throw distances, unacceptable inaccuracies and defects in drop placement occur. In this paper, a new technique based on high-speed imaging and laser optics is presented that allows the visualization of air currents and droplet movement patterns beneath and in the proximity of a printhead and a moving substrate. The images obtained with this technique provide better temporal and spatial resolution than those obtained in previous studies. Tests with two different commercial printheads show that the entrained airflow depends on the interaction with the stream of printed droplets. The formation of unsteady eddies, particularly between nozzle rows, can result in serious errors in drop placement.

High-Speed, Low-Volume Inkjet and its Role in Jet and Flash&amp;#x2122; Imprint Lithography

Imprint lithography is an effective technique for replication of nanoscale features. Jet and Flash&#x2122; Imprint Lithography (J-FIL&#x2122;) uses field-by-field deposition and exposure of a low viscosity resist deposited by inkjet printing onto the substrate. The patterned mask is lowered into the fluid, where capillary action assists to flow the fluid into the relief patterns. Following the filling step, the resist is UV cured, the mask is removed, and a patterned resist is left on the substrate.J-FIL&#x2122; is a technique, where the imprint technology provides the nanoscale pattern resolution while the inkjet technology contributes the throughput that is required for industrial applications. The drop volume and drop placement accuracy of the inkjet-printed resist is critical, allowing the volume to be distributed appropriately across the substrate surface to achieve a uniform target thickness and preventing non-filling of the relief patterns. With J&#x2013; FIL&#x2122;, it is possible to resolve 28 nm structures with residual layer thickness of 13 and 20 nm on 300 mm and 450 mm Si-wafers.In this study, improvements during the filling step are explored for low droplet volumes at high ejection frequencies when using standard printheads with jetting performance of 12 kHz, &lt;3 pL and modified printheads with jetting performance of 28 kHz, &lt;2 pL.