Syringe application

Ease of use 2-6°C storage. Multiple application devices (linear, spray tips, endoscopic, etc.), 20 min preparation time. Set-up time = 30 s-3 min. May wash away in presence of active bleeding. Requires trained personnel to operate equipment. Preparation time required to obtain plasma component. Room temperature storage. 5 min preparation time. Single syringe applicator per kit. Set-up time - 3 min. Effective at site of active bleeding. 

Metallocene PP, particularly s-PP, is one group of such compounds that attracted much attention. The properties of this material are similar to that of thermoplastic elastomers. Metallocene cyclo-olefin is another class that has been used in medical syringe applications. They give high clarity for solution drug prefiUed syringes. 

Several companies manufacture syringe applicators which may be used in manual or automatic modes, such as Fisnar USA, Electron Fusion Devices EFD, Wentworth and Kent Moore (Fig. 5). 

Figure 6 Effect of pressure and time on dot size in syringe application.

Figure 7 Syringe application. Three 740V-SS valves from EFD (USA) dispense microdots of UV curing adhesive on the lens of a barcod scanner (source EFD/USA).

These syringe applicators with very fine needles may apply very small dots or drops down to one hundredth of a milligram. They are widely used in electronics for surface mounting, chips bonding and in jewellery and watches. The application of the adhesive may be controlled with a special camera or an optical fibre detector. The viscosities of the adhesives may range from 100 mPas (cyanoacrylates) to 20,000 mPas (epoxies, silicones). 

Most adhesives dispense well and by using a small tip stringing may be eliminated. Syringe application is also the best method for filling and potting applications, with polyurethanes or silicones. 

This system is similar to the syringe application that we have discussed previously, but the syringes are used in small applications to deliver less than 1 g per part, while the extrusion equipments are used for much larger consumptions. 

In Section 2.4.5, we studied the manual syringe application. For high-speed jobs, such as surface mounting in Electronics, the syringes are operated by high-speed valves and they are installed on a high-speed robot which can move, for instance on the Fisnar robot I and J 2200, at 5 to 500 mm/s X and Y, with a repeatability of +0.01 mm per axis, and a resolution of 0.01 mm for X, Y and Z axis. The parts to be bonded or potted or sealed are placed under the syringe. 

But now, with the robotic syringe application, it is more convenient and cheaper to apply the adhesives as a circular shape at high speeds. 

Table I compiles the relationships between measured forces, impact on syringe application and physics involved. Sustaining forces at velocities encountered during manual use of syringes are related to the hydrodynamic lubrication regime. Lubricant is...

Attribute Impact on Syringe Application Physics of Friction Involved... 

For syringe applications, programmable time/pressure controllers are used to produce beads and dots. An adjustable vacuum also can be used to control drips between dispense cycles. Pressure options relate to material viscosity with zero to one bar specified for low-viscosity applications, for example. Shot duration can typically be controlled between 0.01 and 99.99 s. 

As a preeminent biomaterial, silicones have been the most thoroughly studied polymer over the last half century. From lubrication for syringes to replacements for soft tissue, silicones have set the standard for excellent blood compatibility, low toxicity durability, and bioinertness. Many medical applications would not have been possible without this unique polymer. 

Moreover, such solutions can also canse the sample to crystallize out in the syringe. In this case it is recommended to dilnte the sample and apply larger volumes. Of course, a further possibility is the application of highly concentrated solutions manually with a pipette or, if the sample does not crystallize out in the syringe, semiautomated by the Alltech TLC sample streaker. 

FIGURE 5.7 Eiquipment for manual application, e.g., 500-pl Hamilton syringe (lower), Pasteur pipette (middle), and 2-ml measuring pipette (upper). 

Semiautomatic devices suited for preparative purposes are the CAMAG Linomat 5, the Desaga HPTLC applicator AS 30, and the Alltech TLC sample streaker. For all devices, the syringe has to be filled manually with sample solution and rinsed after sample application. Except for the Alltech TLC sample streaker, each of these instruments can be employed either as software-controlled or as a stand-alone device. The former is more convenient for creation, editing, and saving of the application pattern and instrument parameters. 

Further, in parameter selection, it is recommended to choose the feature empty syringe before filling with next sample to avoid mixing with the rinsing solvent when the sample is withdrawn from the syringe. Small instrument details incorrectly chosen can falsify the yield calculated later on, or result in loss of costly sample. For application of the whole sample volume, i.e., to minimize the vial dead volume, the needle can be adjusted closer to the bottom of the vial, but special care should be taken with that parameter because wrong adjustment may destroy the needle. 

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