You want high purity helium to insure that that there won’t be any mold spores in the tank. If you plan to shoot vertebrate cells you probably won’t need to go above 150 psi. I purchased a regulator that could provide up to 500 psi delivery pressure and purchased a moderately priced one so that I could use it for other applications. The switch doesn’t need to be a momentary switch, but if you use a regular switch, you’ll need to turn the switch back off each time, before you can fire again. The only purpose of the relay it to have consistency in the helium burst from one shot to another. This works, but it is hard to get a reproducible length helium burst that way. The momentary switch is overkill, but originally I was trying to fire the solenoid using the momentary switch without the relay. I mounted the trigger mechanism into an old Starsted blue tip box, but I am sure it can be done more elegantly.
The relay should be set to one shot mode. We usually use 50 milliseconds (005 on the relay). The solenoid won’t fire reliably unless you use at least 30 to40 milliseconds fireing time. The relay can be set to fire by 10 millisecond intervals from 0.01 to 10.00 seconds. Note that the 120 V AC current powers both the relay and the solenoid. The wiring can be figured out from looking at the photograph. The solenoid is wired to a trigger that consists of a momentary swich which fires a one-shot relay swich. I am securing the solenoid using a mounting clamp attached to a ring stand so I can adjust the height easily. The filter is screwed into the female end, and we fire from about 7 cm using aa 300- 400 psi burst for 50 ms. The ethanol doesn’t cause any harm andmost of it probably evaporates before hitting the cells during firing. The gold spreads relatively evenly onto the plastic support using this volume. One could purchase a solenoid valve that will hold 750 psi for essentially the same price (see options in parts list).ĭNA-covered gold particles are loaded onto the Millipore filter holder male end in 5 to 10 microliters of ethanol.
It holds the pressure now, but may not forever. I originally purchased a 300 psi solenoid valve, but I am now firing at 400 psi using the 300 psi valve.
For a more condensed spray of gold, the tip can be left uncut. elegans applications, the Swinnex filter bottom is cut so that the gold spread is more diffuse. A more elegant and expensive approach is to purchase a 1/8″ NPTM to M Luer locking adapter from Millipore (see parts list). It then fits tightly into the Parker O-ring fitting. The cheap way to connect to the Swinnex filter to the solenoid is to shave of the threading on the Swinnex filter. On the input side the solenoid is attached to tubing to connect to the regulator, on the other side it is attached to a Swinnex filter holder which acts as the support to load the gold or tungsten particles you wish to fire. The apparatus consists of a solenoid valve with 1/8 inch NPT female fittings. NOTE: Helium tank and regulator are not shown
0 kommentar(er)
