Showing papers on "Blisters published in 2016"

Blister pouches for effective reagent storage on microfluidic chips for blood cell counting

Abstract: We present the analysis of blister pouches for reagent storage and release into microfluidic devices towards point-of-care blood cell counting applications. Blister pouches provide an effective reagent storage mechanism and can be mounted onto microfluidic cartridges directly. Reagents can be released from blister pouches through automated or manual compression and consequent rupturing of the pouches. A microfluidic device for metering of blister pouch contents was developed and investigated as part of this work, as precise volumes of reagents are often required when performing reactions, and particularly for blood cell counting applications which are the focus of this study. The metering device shows high accuracy and repeatability with an error of 1.93% and standard deviation of 3.1% across 30 test results. This work also investigates important blister pouch characteristics for three different types of blister pouch foil materials, including forces required to burst the blister, as well as shelf life and reagent compatibility of the blisters. Typical forces required are in the range of 25–35 N depending on the blister foil material used. Blister shelf life can be greatly affected by the reagent being stored, and thus, the blister foil material choice is crucial. This work provides a clear understanding of the implementation required to ensure that the blister pouches can be effectively used on microfluidic chips, with an example application area being point-of-care diagnostics.

Combined effects of crystallography, heat treatment and surface polishing on blistering in tungsten exposed to high-flux deuterium plasma

Abstract: For tungsten exposed to low-energy hydrogen-plasmas, it has been thought that grains with surface normal are most susceptible to blistering while those with surface normal are virtually impervious to it. Here, we report results showing that non-uniformity of blister distribution depends on the state of the surface due to polishing. In electrochemically polished material blisters appear on the grains with all orientations, while in mechanically polished material blister-free areas associated with particular orientations emerge. On the other hand, blistering is shown to have a strong dependence on the level of deformation within particular grains in partially recrystallized material.

A model for pressurized hydrogen induced thin film blisters

Abstract: We introduce a model for hydrogen induced blister formation in nanometer thick thin films. The model assumes that molecular hydrogen gets trapped under a circular blister cap causing it to deflect elastically outward until a stable blister is formed. In the first part, the energy balance required for a stable blister is calculated. From this model, the adhesion energy of the blister cap, the internal pressure and the critical H-dose for blister formation can be calculated. In the second part, the flux balance required for a blister to grow to a stable size is calculated. The model is applied to blisters formed in a Mo/Si multilayer after being exposed to hydrogen ions. From the model the adhesion energy of the Mo/Si blister cap was calculated to be around 1.05 J/m2 with internal pressures in the range of 175-280 MPa. Based on the model a minimum ion dose for the onset of blister formation was calculated to be d = 4.2*10^18 ions/cm2. From the flux balance equations the diffusion constant for the Mo/Si blister cap was estimated to be D_H2 = (10+-1) *10^18 cm2/s.

A model for pressurized hydrogen induced thin film blisters

Abstract: We introduce a model for hydrogen induced blister formation in nanometer thick thin films. The model assumes that molecular hydrogen gets trapped under a circular blister cap causing it to deflect elastically outward until a stable blister is formed. In the first part, the energy balance required for a stable blister is calculated. From this model, the adhesion energy of the blister cap, the internal pressure, and the critical H-dose for blister formation can be calculated. In the second part, the flux balance required for a blister to grow to a stable size is calculated. The model is applied to blisters formed in a Mo/Si multilayer after being exposed to hydrogen ions. From the model, the adhesion energy of the Mo/Si blister cap was calculated to be around 1.05 J/m2 with internal pressures in the range of 175–280 MPa. Based on the model, a minimum ion dose for the onset of blister formation was calculated to be d = 4.2 × 1018 ions/cm2. From the flux balance equations, the diffusion constant for the Mo/Si blister cap was estimated to be D H 2 =(10±1)×10 −18 cm 2 /s DH2=(10±1)×10−18 cm2/s .

Snap Transitions of Pressurized Graphene Blisters

Abstract: Blister tests are commonly used to determine the mechanical and interfacial properties of thin film materials with recent applications for graphene. This paper presents a numerical study on snap transitions of pressurized graphene blisters. A continuum model is adopted combining a nonlinear plate theory for monolayer graphene with a nonlinear traction–separation relation for van der Waals interactions. Three types of blister configurations are considered. For graphene bubble blisters, snap-through and snap-back transitions between pancake-like and dome-like shapes are predicted under pressurecontrolled conditions. For center-island graphene blisters, snap transitions between donut-like and dome-like shapes are predicted under both pressure and volume control. Finally, for the center-hole graphene blisters, growth is stable under volume or N-control but unstable under pressure control. With a finite hole depth, the growth may start with a snap transition under N-control if the hole is relatively deep. The numerical results provide a systematic understanding on the mechanics of graphene blisters, consistent with previously reported experiments. Of particular interest is the relationship between the van der Waals interactions and measurable quantities in corresponding blister tests, with which both the adhesion energy of graphene and the equilibrium separation for the van der Waals interactions may be determined. In comparison with approximate solutions based on membrane analyses, the numerical method offers more accurate solutions that may be used in conjunction with experiments for quantitative characterization of the interfacial properties of graphene and other two-dimensional (2D) membrane materials. [DOI: 10.1115/1.4033305]

Blistering during the atomic layer deposition of iridium

Abstract: The authors report on the formation of blisters during the atomic layer deposition of iridium using iridium acetylacetonate and oxygen precursors. Films deposited on fused silica substrates led to sparsely distributed large blisters while in the case of silicon with native oxide additional small blisters with a high density was observed. It is found that the formation of blisters is favored by a higher deposition temperature and a larger layer thickness. Postdeposition annealing did not have a significant effect on the formation of blisters. Finally, changing purge duration during the film growth allowed us to avoid blistering and evidenced that impurities released from the film in gas phase were responsible for the formation of blisters.

Etiological Foundation for Practical Strategies to Prevent Exercise-Related Foot Blisters.

Abstract: This work outlines the etiological factors for exercise-related foot blisters and the pertinent prevention strategies related to these causes. Blisters result from shear forces within the epidermis causing cell necrosis. The extent of skin shear is influenced by friction at the skin and other interfaces, various skin characteristics, bony movement, and the shear modulus of the foot ware. The number of shear cycles is another factor in the development of blisters. Key preventative strategies include limiting the number of shear cycles, avoiding moisture and particulate accumulation next to the skin, frequent use of skin lubricants, elimination of pressure points through proper fitting and broken in shoes and callous removal, use of low shear modulus insoles, and induction of skin adaptations through proper training. Other methods requiring further research, but with theoretical support, include the use of taping and low friction patches over high-friction areas, and double-layered or toe socks.

Origin of microplasma instabilities during DC operation of silicon based microhollow cathode devices

Abstract: The failure mechanisms of micro hollow cathode discharges (MHCD) in silicon have been investigated using their I-V characteristics, high speed photography and scanning electron microscopy. Experiments were carried out in helium. We observed I–V instabilities in the form of rapid voltage decreases associated with current spikes. The current spikes can reach values more than 100 times greater than the average MHCD current. (The peaks can be more than 1 Ampere for a few 10’s of nanoseconds.) These current spikes are correlated in time with 3–10 μm diameter optical flashes that occur inside the cavities. The SEM characterizations indicated that blister-like structures form on the Si surface during plasma operation. Thin Si layers detach from the surface in localized regions. We theorize that shallow helium implantation occurs and forms the ‘blisters’ whenever the Si is biased as the cathode. These blisters ‘explode’ when the helium pressure inside them becomes too large leading to the transient micro-arcs seen in both the optical emission and the I–V characteristics. We noted that blisters were never found on the metal counter electrode, even when it was biased as the cathode (and the Si as the anode). This observation led to a few suggestions for delaying the failure of Si MHCDs. One may coat the Si cathode (cavities) with blister resistant material; design the MHCD array to operate with the Si as the anode rather than as the cathode; or use a gas additive to prevent surface damage. Regarding the latter, tests using SF6 as the gas additive successfully prevented blister formation through rapid etching. The result was an enhanced MHCD lifetime.

Impact on the deuterium retention of simultaneous exposure of tungsten to a steady state plasma and transient heat cycling loads

Abstract: The impact on the deuterium retention of simultaneous exposure of tungsten to a steady-state plasma and transient cyclic heat loads has been studied in the linear PSI-2 facility with the main objective of qualifying tungsten (W) as plasma-facing material. The transient heat loads were applied by a high-energy laser, a Nd:YAG laser (λ = 1064 nm) with an energy per pulse of up to 32 J and a duration of 1 ms. A pronounced increase in the D retention by a factor of 13 has been observed during the simultaneous transient heat loads and plasma exposure. These data indicate that the hydrogen clustering is enhanced by the thermal shock exposures, as seen on the increased blister size due to mobilization and thermal production of defects during transients. In addition, the significant increase of the D retention during the simultaneous loads could be explained by an increased diffusion of D atoms into the W material due to strong temperature gradients during the laser pulse exposure and to an increased mobility of D atoms along the shock-induced cracks. Only 24% of the retained deuterium is located inside the near-surface layer (d<4 μm). Enhanced blister formation has been observed under combined loading conditions at power densities close to the threshold for damaging. Blisters are not mainly responsible for the pronounced increase of the D retention.

Connected sensor substrate for blister packs

Abstract: A blister pack for dispensing medication comprises a substantially flat backing, blisters formed on the backing, breakable resistive traces, conductive traces, a power source for applying electrical power to the traces, and a controller. The blisters and the backing form cavities for containing the medication, and each blister is coupled with another blister to form pairs of blisters. Resistive traces are applied to the backing under each blister. For each pair of blisters, the resistive traces under a first blister of the pair of blisters is connected in parallel by the conductive traces with the resistive traces under a second blister of the pair of blisters. The controller detects breakage of the resistive traces under the blisters for each pair of blisters by measuring the voltage across the resistive traces under each pair of blisters, and communicate the status to a remote server for instant analysis and reporting to parties of interest.

Reduction of Blister Formation Time in Suction Blister Epidermal Grafting in Vitiligo Patients Using a Household Hair Dryer.

Abstract: Background: Suction blister epidermal grafting (SBEG) is a simple and effective way of surgical repigmentation in vitiligo. The major problem faced is the time taken for the formation of blisters. Temperature at the suction site is one of the factors affecting the blister formation time. Aims and Objectives: To reduce the blister formation time in SBEG by increasing the surface temperature to 44°C. Materials and Methods: This is a left-right comparison study. Total seven patients with lip vitiligo involving both the angles of lips were enrolled. Suction syringes were applied on both the thighs of all the patients. On the right thigh, blisters were raised as per the procedure standardised by Gupta et al. On the left thigh, similar procedure was used, but a hair dryer was used additionally to increase the surface temperature of the skin to 44°C. The time taken for the formation of well-formed, dome-shaped, unilocular blister was noted. Results: The mean time taken for the formation of blister on the right thigh was 121.1 ± 6.2 min and on the left thigh was 69.6 ± 5.4 min. All the seven patients were started on PUVASOL after SBEG. There was complete repigmentation of the grafted sites in all the patients after 2 months. Conclusion: Hair dryer is easily available, affordable and simple to use and the time saved during the procedure is quite significant.

Influence of hydrogen fluence on surface blistering of H and He co-implanted Ge

Abstract: The effect of hydrogen fluence on surface blistering of H and He co-implanted Ge is investigated using atom force microscope, X-ray diffraction and transmission electron microscopy. With a fixed He, we find that for 1 × 10 16 cm −2 H implantation fluence, only a few small dome-shaped blisters appear, for 3 × 10 16 cm −2 H implantation fluence, large blisters as well as craters are formed, while for 5 × 10 16 cm −2 H implantation fluence, no blisters can be observed. The strain evolution and platelet forming tendency are found to be relevant for the different blistering phenomenon. The weak blistering phenomenon for 1 × 10 16 cm −2 H implantation fluence may be attributed to less “free” H for the building up of internal pressure of platelets and the sustained growth of platelets. While the absence of blistering phenomenon for 5 × 10 16 cm −2 H implantation fluence is likely due to the retarded relief of the decreased uniform compressive stress throughout the damage region.

Dielectric Coating Thermal Stabilization During GaAs-Based Laser Fabrication for Improved Device Yield

Abstract: The quality and yield of GaAs-based ridge waveguide devices fabricated at MIT Lincoln Laboratory were negatively impacted by the random lot-to-lot appearance of blisters in the front-side contact metal. The blisters signaled compromised adhesion between the front-side contact metal, underlying SiO2 dielectric coating, and semiconductor surface. A thermal-anneal procedure developed for the fabrication of GaAs slab coupled optical waveguide (SCOW) ridge waveguide devices stabilizes the SiO2 dielectric coating by means of outgassing and stress reduction. This process eliminates a primary source of adhesion loss, as well as blister generation, and thereby significantly improves device yield. Stoney’s equation was used to analyze stress-induced bow in device wafers fabricated using this stabilization procedure. This analysis suggests that changes in wafer bow contribute to the incidence of metal blisters in SCOW devices.

Dielectric Coating Thermal Stabilization During GaAs-Based Laser Fabrication for Improved Device Yield

Abstract: The quality and yield of GaAs-based ridge waveguide devices fabricated at MIT Lincoln Laboratory were negatively impacted by the random lot-to-lot appearance of blisters in the front-side contact metal. The blisters signaled compromised adhesion between the front-side contact metal, underlying SiO2 dielectric coating, and semiconductor surface. A thermal-anneal procedure developed for the fabrication of GaAs slab coupled optical waveguide (SCOW) ridge waveguide devices stabilizes the SiO2 dielectric coating by means of outgassing and stress reduction. This process eliminates a primary source of adhesion loss, as well as blister generation, and thereby significantly improves device yield. Stoney’s equation was used to analyze stress-induced bow in device wafers fabricated using this stabilization procedure. This analysis suggests that changes in wafer bow contribute to the incidence of metal blisters in SCOW devices.

Managing fever blisters in the pharmacy

Abstract: Fever blisters, also known as cold sores or herpes labialis, are small, painful, fluid filled, and appear in groups on the lips and around the mouth. They form into scabs over a few days, and usually heal any time between several days and two weeks. Fever blisters are caused by a virus which is not completely eliminated by the body’s defenses. Thus, they often recur.

Conditions for the early onset of blisters during heat treatments of Al-Si-Cu CAST PART

Abstract: The evolution of subsurface pressurized pores, originating blisters during heat treatment cycles, on High Pressure Die Cast components made of Al-Si-Cu alloys was studied using a Finite Element Model in order to understand under which conditions blister form even below 400°C. The initial defect geometry, depth, inner pressure and the maximum temperature of the thermal cycle were varied in limited ranges, while the material was modelled as elastoplastic, considering creep effects negligible. Results suggested that blisters develop as a result of high plastic strain accumulation in localized regions lying between the pore and the outer surface and that blisters can form even at temperatures of 350-370°C. The simulations were experimentally validated by two sets of experiments carried out on cast parts, monitoring the surface and volume evolution of subsurface defects coupled by optical microscopy and microtomography analyses.

Effect of inelastic and elastic energy losses of Xe ions on the evolution of hydrogen blisters in silicon

Abstract: We analyze the effect of irradiation by heavy ions on the formation of blisters on the silicon surface preliminarily ion-doped with hydrogen. An attempt is made at differentiating inelastic and elastic processes of interaction between ions and Si atoms using bombardment of the sample with high-energy charged particles through a bent absorbing filter by varying the radiation doses and the energy of bombarding Xe ions. It is found that irrespective of specific ionization energy losses of heavy ions, the blister formation is completely suppressed in the zone of the inelastic interaction during postradiation annealing. Conversely, stimulated development of hydrogen porosity takes place at the same time in the zone of elastic interaction, which is manifested in the form of blisters and flaking.

Mixed aluminum precursor in the atomic layer deposited Al 2 O 3 for effective silicon emitter passivation

Abstract: In this contribution, we have studied the impact of aluminum precursor of atomic layer deposited (ALD) AI2O3 on the passivation quality of silicon solar cell emitters. Aluminum precursors, Trimethylaluminum (TMA) and Dimethylaluminum chloride (DMACl), and their different combinations were used to deposit Al 2 O 3 layers on both phosphorus and boron implanted emitters. In addition to measuring the passivation quality, the wafers experienced thermal stability investigation. In all wafers, Al 2 O 3 resulted in better emitter saturation current as compared to thermal oxide resulting from ion implantation drive-in anneal. On industrial type of emitters, values around J oe at 60 fA/cm2 were obtained. The impact of aluminium source was not as high as expected, however, we found that aluminium precursor has a high impact on the formation of so-called blisters. We show that the blisters can be greatly suppressed using DMACl as the aluminium precursor while TMA results in the formation of high-density and large-size blisters. Our PERC solar cell with the DMACl in the ALD process showed similar passivation quality as the TMA-based process.

Blister cutting mechanism of paper plastic packaging machine

Abstract: The invention discloses a blister cutting mechanism of a paper plastic packaging machine The blister cutting mechanism comprises a rack, a cutting device, a waste collecting device and a blister conveying device The blister cutting mechanism is characterized in that the cutting device comprises a blister indentation part and a blister separation part, wherein the blister indentation part comprises an indentation knife and a mould base matched with the indentation knife; the blister separation part comprises a movable blister supporting plate and a plate conveying rod for conveying a blister onto the blister supporting plate; a groove matched with the blister is formed in the blister supporting plate; the plate conveying rod is arranged above the blister supporting plate and is connected with a power source for driving the blister supporting plate to lift; and during the working condition of blister separation, the blister supporting plate upwards moves to support the blister, and the plate conveying rod downwards moves to convey the blister into the groove in the blister supporting plate By using the blister cutting mechanism, small blisters are machined, and the problem of small blister cutting difficulty in the prior art is solved