scholarly journals Blister-Actuated LIFT Printing for Multiparametric Functionalization of Paper-Like Biosensors

Micromachines ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 221 ◽  
Author(s):  
Lars Hecht ◽  
Korbinian Rager ◽  
Martynas Davidonis ◽  
Patricia Weber ◽  
Günter Gauglitz ◽  
...  
Keyword(s):  
Color Change ◽  
Laser Pulses ◽  
Active Components ◽  
Buffer Solution ◽  
Contact Printing ◽  
Micro Channels ◽  
Custom Made ◽  
Forward Transfer ◽  
Lateral Flow Test ◽  
Active Detection

Laser induced forward transfer (LIFT) is a flexible digital printing process for maskless, selective pattern transfer, which uses single laser pulses focused through a transparent carrier substrate onto a donor layer to eject a tiny volume of the donor material towards a receiver substrate. Here, we present an advanced method for the high-resolution micro printing of bio-active detection chemicals diluted in a viscous buffer solution by transferring droplets with precisely controllable volumes using blister-actuated LIFT (BA-LIFT). This variant of the LIFT process makes use of an intermediate polyimide layer partially ablated by the laser pulses. The expanding gaseous ablation products lead to blisters in the polyimide and ejection of droplets from the subjacent viscous solution layer. A relative movement of donor and receiver substrates for the transfer of partially overlapping pixels is realized with a custom-made positioning system. Using a specially developed donor ink containing bio-active components presented method allows to transfer droplets with well controllable volumes between 20 fL and 6 pL, which is far more precise than other methods like inkjet or contact printing. The usefulness of the process is demonstrated by locally functionalizing laser-structured nitrocellulose paper-like membranes to form a multiparametric lateral flow test. The recognition zones localized within parallel micro channels exhibit a well-defined and homogeneous color change free of coffee-ring patterns, which is of utmost importance for reliable optical readout in miniature multiparametric test systems.

Effect of 10% and 15% Carbamide Peroxide on Fracture Toughness of Human Dentin In Situ

2013 ◽  
Vol 38 (2) ◽  
pp. 142-150 ◽  
Author(s):  
LE Tam ◽  
P Bahrami ◽  
O Oguienko ◽  
H Limeback
Keyword(s):  
Fracture Toughness ◽  
Placebo Group ◽  
Color Change ◽  
Carbamide Peroxide ◽  
Tooth Sensitivity ◽  
Custom Made ◽  
Dental Hard Tissues ◽  
Significant Difference

SUMMARY Purpose Although damage to the structural integrity of the tooth is not usually considered a significant problem associated with tooth bleaching, there have been some reported negative effects of bleaching on dental hard tissues in vitro. More studies are needed to determine whether the observed in vitro effects have practical clinical implications regarding tooth structural durability. Objectives This in situ study evaluated the effect of 10% and 15% carbamide peroxide (CP) dental bleach, applied using conventional whitening trays by participants at home, on the fracture toughness of dentin. Methods Ninety-one adult volunteers were recruited (n ≈ 30/group). Compact fracture toughness specimens (approximately 4.5 × 4.6 × 1.7 mm) were prepared from the coronal dentin of recently extracted human molars and gamma-radiated. One specimen was fitted into a prepared slot, adjacent to a maxillary premolar, within a custom-made bleaching tray that was made for each adult participant. The participants were instructed to wear the tray containing the dentin specimen with placebo, 10% CP, or 15% CP treatment gel overnight for 14 nights and to store it in artificial saliva when not in use. Pre-bleach and post-bleach tooth color and tooth sensitivity were also evaluated using ranked shade tab values and visual analogue scales (VASs), respectively. Within 24–48 hours after the last bleach session, the dentin specimens were tested for fracture toughness using tensile loading at 10 mm/min. Analysis of variance, Kruskal-Wallis, χ2, Tukey's, and Mann-Whitney U tests were used for statistical analysis. The level of significance was set at p<0.05 for all tests, except for the Mann-Whitney U tests, which used a Bonferroni correction for post hoc analyses of the nonparametric data (p<0.017). Results The placebo, 10% CP, and 15% CP groups contained 30, 31, and 30 participants, respectively. Mean fracture toughness (+ standard deviation) for the placebo, 10% CP, and 15% CP groups were 2.3 ± 0.9, 2.2 ± 0.7, and 2.0 ± 0.5 MPa*m1/2 respectively. There were no significant differences in mean fracture toughness results among the groups (p=0.241). The tooth sensitivity VAS scores indicated a significantly greater incidence (p=0.000) and degree of tooth sensitivity (p=0.049 for VAS change and p=0.003 for max VAS) in the bleach groups than in the placebo group. The color change results showed generally greater color change in the bleach groups than in the placebo group (p=0.008 for shade guide determination and p=0.000 for colorimeter determination). Conclusions There were no significant differences in in situ dentin fracture toughness results among the groups. The results of this study provide some reassurance that dentin is not overtly weakened by the bleaching protocol used in this study. However, the lack of a statistically significant difference cannot be used to state that there is no effect of bleach on dentin fracture toughness.

Preparation of porphyrin modified CO9S8 nanocomposites and application for colorimetric biosensing of H2O2

2018 ◽  
Vol 22 (09n10) ◽  
pp. 935-943 ◽  
Author(s):  
Yan Gao ◽  
Chunqiao Jin ◽  
Miaomiao Chen ◽  
Xixi Zhu ◽  
Min Fu ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Peroxidase Activity ◽  
Catalytic Mechanism ◽  
Color Change ◽  
Colorimetric Detection ◽  
Buffer Solution ◽  
Hydrogen Peroxide Detection ◽  
Steady State Kinetics ◽  
One Step

Hydrogen peroxide detection has been widely applied in the fields of biology, medicine, and chemistry. Colorimetric detection of hydrogen peroxide has proven to be a fast and convenient method. In this work, 5,10,15,20-tetrakis(4-chlorophenyl) porphyrin modified Co[Formula: see text]S[Formula: see text] nanocomposites (H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text] were prepared via a facile one-step hydrothermal method. H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text] nanocomposites were demonstrated to possess an enhanced mimetic peroxidase activity toward the substrate, 3,3[Formula: see text],5,5[Formula: see text]-tetramethylbenzidine (TMB), which can be oxidized to oxTMB (oxidized TMB) in a buffer solution of hydrogen peroxide with a color change from colorless to blue. The catalytic activity of H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text] was further analyzed by steady-state kinetics, and H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text] had high affinity towards both TMB and H[Formula: see text]O[Formula: see text]. Furthermore, fluorescence and ESR data revealed that the catalytic mechanism of the peroxidase activity of H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text] is due to hydroxyl radicals generated from decomposition of H[Formula: see text]O[Formula: see text]. Based on the catalytic activity of H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text], a sensitive colorimetric sensor of H[Formula: see text]O[Formula: see text] with a detection limit of 6.803 [Formula: see text]M as well as a range of 7–100 [Formula: see text]M was designed.

Microfluidic Device for Synthesis of Lipid Bi-Layers

2008 ◽  
Author(s):  
B. M. R. U. Banneyake ◽  
Debjyoti Banerjee
Keyword(s):  
Organic Solvent ◽  
Microfluidic Device ◽  
Single Channel ◽  
Hydrophobic Surface ◽  
Mirror Image ◽  
Buffer Solution ◽  
Pump System ◽  
Glass Substrates ◽  
Micro Channels ◽  
Cell Components

Lipid bi-layers are ubiquitous components of biological cells — and are found in variety of cell components ranging from cell membranes to membranes of organelles inside the cells. In biological membranes, lipid bi-layer membranes carry membrane proteins, which serve as single channel nanopores that are used to study transport of proteins and characterize the properties of proteins. However, lipid bi-layers have very short half lives, which are usually less than an hour. The lipid bi-layers are usually obtained by physico-chemical interactions between a lipid containing organic solvent, an aqueous buffer solution and a hydrophobic surface. We have developed a continuous flow through microfluidic device using pressure driven flow (by means of a tandem syringe pump system) for synthesis of lipid bi-layers. The microfluidic device consists of two glass substrates with micro-channels and microchambers microfabricated using photolithography and wet glass etching. The microchannels in each substrate is in the form of “+” shape and form a mirror image of each other. A Teflon sheet (∼200 microns thickness) is sandwiched between the glass substrates with a ∼200 microns diameter hole etched in the center to communicate with the two sets of microchannels. A lipid solution in an organic solvent (Pentane) and KCl buffer solution are alternately flown through the legs of the microchannel. The conductivity of the buffer is monitored using a current amplifier. The formation of the lipid bi-layer is confirmed by monitoring the resistivity and the impedance to high frequency electrical oscillations. The flow rate in the microfluidic device is optimized to obtain the lipid bi-layer.

scholarly journals Overlapping Limitations for ps-Pulsed LIFT Printing of High Viscosity Metallic Pastes

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 168 ◽  
Author(s):  
David Munoz-Martin ◽  
Yu Chen ◽  
Miguel Morales ◽  
Carlos Molpeceres
Keyword(s):  
Laser Pulse ◽  
Short Distance ◽  
Laser Pulse Energy ◽  
Laser Pulses ◽  
High Viscosity ◽  
Single Step ◽  
High Speeds ◽  
Forward Transfer ◽  
Micron Size ◽  
Interference Problems

Laser-induced forward transfer (LIFT) technique has been used for printing a high viscosity (250 Pa·s) commercial silver paste with micron-size particles (1–4 µm). Volumetric pixels (voxels) transferred using single ps laser pulses are overlapped in order to obtain continuous metallic lines. However, interference problems between successive voxels is a major issue that must be solved before obtaining lines with good morphologies. The effects of the laser pulse energy, thickness of the donor paste film, and distance between successive voxels on the morphology of single voxels and lines are discussed. Due to the high viscosity of the paste, the void in the donor film after a printing event remains, and it negatively affects the physical transfer mechanism of the next laser pulses. When two laser pulses are fired at a short distance, there is no transfer at all. Only when the pulses are separated by a distance long enough to avoid interference but short enough to allow overlapping (≈100 µm), is it possible to print continuous lines in a single step. Finally, the knowledge obtained has allowed the printing of silver lines at high speeds (up to 60 m/s).

scholarly journals Dual-Channel Probe of Carbon Dots Cooperating with Lanthanide Complex Employed for Simultaneously Distinguishing and Sequentially Detecting Tetracycline and Oxytetracycline

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 128
Author(s):  
Lei Jia ◽  
Zhitao Xu ◽  
Rujie Chen ◽  
Xiangzhen Chen ◽  
Jun Xu
Keyword(s):  
Antimicrobial Agents ◽  
Fluorescence Probe ◽  
Color Change ◽  
Logic Gate ◽  
Lanthanide Complex ◽  
High Sensitivity ◽  
Inner Filter Effect ◽  
Antenna Effect ◽  
Buffer Solution ◽  
Dual Channel

Tetracycline (TC) and oxytetracycline (OTC) are the most widely used broad-spectrum antimicrobial agents in tetracycline drugs, and their structures and properties are very similar, so it is a great challenge to distinguish and detect these two antibiotics with a single probe at the same time. Herein, a dual-channel fluorescence probe (SiCDs@mMIPs-cit-Eu) was developed by integrating two independent reaction sites with SiCDs-doped mesoporous silica molecular imprinting group and europium complex group into a nanomaterial. The synergistic influence of inner filter effect and “antenna effect” can be guaranteed to solve the distinction between TC and OTC. Moreover, this novel strategy can also sequentially detect TC and OTC in buffer solution and real samples with high sensitivity and selectivity. This method revealed good responses to TC and OTC ranging from 0 to 5.5 μM with a detection limit of 5 and 16 nM, respectively. Combined with the smartphone color-scanning application, the portable and cheap paper-based sensor was designed to realize the multi-color visual on-site detection of TC and OTC. In addition, the logic gate device was constructed according to the fluorescence color change of the probe for TC and OTC, which provided the application possibility for the intelligent detection of the probe.

scholarly journals Growing neuronal islands on multi-electrode arrays using an Accurate Positioning-μCP device

2015 ◽  
Author(s):  
Robert Samhaber ◽  
Manuel Schottdorf ◽  
Ahmed El Hady ◽  
Kai Broeking ◽  
Andreas Daus ◽  
...  
Keyword(s):  
Cell Culture ◽  
Neuronal Networks ◽  
Standard Cell ◽  
Electrode Arrays ◽  
Unit Recording ◽  
Contact Printing ◽  
Novel Approach ◽  
Custom Made ◽  
Typical Cell

Multi-electrode arrays (MEAs) allow non-invasive multi-unit recording in-vitro from cultured neuronal networks. For sufficient neuronal growth and adhesion on such MEAs, substrate preparation is required. Plating of dissociated neurons on a uniformly prepared MEA's surface results in the formation of spatially extended random networks with substantial inter-sample variability. Such cultures are not optimally suited to study the relationship between defined structure and dynamics in neuronal networks. To overcome these shortcomings, neurons can be cultured with pre-defined topology by spatially structured surface modification. Spatially structuring a MEA surface accurately and reproducibly with the equipment of a typical cell-culture laboratory is challenging. In this paper, we present a novel approach utilizing micro-contact printing (μCP) combined with a custom-made device to accurately position patterns on MEAs with high precision. We call this technique AP-μCP (accurate positioning micro-contact printing). Other approaches presented in the literature using μCP for patterning either relied on facilities or techniques not readily available in a standard cell culture laboratory, or they did not specify means of precise pattern positioning. Here we present a relatively simple device for reproducible and precise patterning in a standard cell-culture laboratory setting. The patterned neuronal islands on MEAs provide a basis for high throughput electrophysiology to study the dynamics of single neurons and neuronal networks.

Study of Overlapping Adjacent Jets for Effective Laser-Induced Forward Transfer Printing

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Marc Sole-Gras ◽  
Ruitong Xiong ◽  
Changxiao Liang ◽  
William Roorda ◽  
Hitomi Yamaguchi ◽  
...  
Keyword(s):  
Laser Pulses ◽  
Time Interval ◽  
Material System ◽  
Laser Printing ◽  
Optical Scanner ◽  
Material Deposition ◽  
Forward Transfer ◽  
Laser Frequencies ◽  
Deposition Processes ◽  
Viscous Solutions

Abstract Laser-induced forward transfer (LIFT) is a well-established, versatile additive manufacturing technology for orifice-free printing of highly viscous solutions and suspensions. In order to improve the efficiency of point-wise LIFT printing, an optical scanner is integrated into the laser printing system to enable the formation of overlapping adjacent jets used for deposition. The objective of this study is to evaluate the ejection behavior and deposition performance under such conditions during LIFT printing for further improvement. The effects of the overlap of adjacent jets are investigated in terms of jet formation and material deposition processes, capturing the jet tilting phenomenon caused by the perturbance induced by previously formed jet(s). The feasibility of optical scanner-assisted LIFT printing of viscous metal-based ink suspension has been successfully demonstrated during conductive line printing with induced overlapping jets. Investigation of various overlap ratios of adjacent jets found that a 30% jet overlap and a 133 µs time interval between laser pulses are optimal, in terms of deposition quality and ejection stability, even when a tilted jet ejection is present for the laser and material system in this study. Furthermore, multilayer polygonal and interdigitated structures are successfully deposited under these identified printing conditions. With the inclusion of an optical scanner, LIFT printing efficiency for viscous inks can be improved as the usage of higher laser frequencies is enabled, providing a faster orifice-free laser printing methodology.

Laser-induced forward transfer of 40 nm Chromium film using ultrashort laser pulses

2006 ◽  
Author(s):  
Anne-Patricia Alloncle ◽  
Renaud Bouffaron ◽  
Jörg Hermann ◽  
Marc Sentis
Keyword(s):  
Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Chromium Film ◽  
Forward Transfer ◽  
Ultrashort Laser

Plume and Jetting Regimes in a Laser Based Forward Transfer Process as Observed by Time-Resolved Optical Microscopy

2001 ◽  
Vol 698 ◽  
Author(s):  
D. Young ◽  
R. C. Y. Auyeung ◽  
A. Piqué ◽  
D. B. Chrisey ◽  
H. Denham ◽  
...  
Keyword(s):  
Viscous Fluid ◽  
Optical Microscopy ◽  
Transfer Process ◽  
High Speed ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Laser Evaporation ◽  
Direct Write ◽  
Time Resolved ◽  
Forward Transfer

ABSTRACTMatrix-Assisted Pulsed Laser Evaporation Direct-Write was investigated by ultra high-speed optical microscopy. A layer of viscous fluid was irradiated with 355nm, 30 ns laser pulses in a laser-forward transfer configuration. The fluid response as a function of fluence was studied, and several distinct regimes of behavior were observed: plume, jetting and sub-threshold. However, the transition between plume and jetting regimes was not readily evident in a study of transfer pixel area vs. fluence, which may be explained by material-substrate interactions.

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