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Home FAQs Applications
Applications 2018-01-21T22:12:01+00:00

 Applications

This FAQ category contains post about pumping applications. How to interface pumps with microscopes, and other devices. Tips on how to work with pumps in the area containing a MRI machine would be a fine example of an FAQ article here.

Application Notes – Start by reading this 2018-01-16T20:14:22+00:00

This FAQ section is titled Application Notes.

As folks all over the world download and purchase my software – they come back to me and ask for specific help with their pump’s application. I also build pumping applications for $. All of this means I am collecting some very useful tips and tricks for different applications of pumps.

These Application Notes are a place to capture my notes so that I may pass on what I have learnt or done. Over time, as I revisit applications I will add to these application specific notes.

When you read these application notes, bear in mind:

  • Any particular note is not written to solve your exact issue – so don’t read them expecting all the answers
  • I am not claiming expertise or experience in your field – only the control and operation of  pumps.
  • I am here  to help when I can – so if you cant find an answer to your problem – contact me.

Contribute

If I have missed something or you know something that could be added to these notes – let me know. Let’s share our knowledge so that we can all get on with getting to the experimental outcomes.

Connecting Microscopes and Pumps 2018-01-27T02:24:34+00:00

Microscopes Controlling Your Pump – How do you do that?

This application note is for microscope owners who wish to pump fluids under the control of their microscopes. There are a number of reasons they wish to irrigate slides ranging from simply wetting their sample over time, applying solutions whilst they observe the effect on cells and small creatures, or to watch micro-fluidic level interactions.

Typical Flows Required

As a broad statement, microscope owners tend to want to create long term small flows or periodic washes or flushes. The flows are usually not complex – a single rate and volume but triggered by their viewing activities. Most commonly only a single pump is controlled.

More Than One Punp?

If your microscope only has the single digital output signal, and you wish to use more than one pump, you will need to adopt a pump control strategy. There are two  – the all pumps at one time – parallel control strategy and the Daisy Chain strategy where a pump signals the next pump when it has finished it’s infusion. I would have liked to call this the serial strategy but I want to avoid using the word serial here – because well, we have a serial port involved.

Parallel Strategy

All pumps are wired to receive the same digital input on their foot-switch input pin, and then each pump’s pumping program (PPL) is written as though it were the only pump involved – ie a pump will pause for a length of time to allow another pump to deliver it’s flow and then infuse it’s own rate and volume. These pause times are easily calculated.

Multiple pump file sets

Multiple pump file sets

Be sure to use SyringePumpPro’s pump recipes method to upload the individual pump’s PPL files as a set – to guarantee pumps all receive the correct pump program each and every time.

Daisy Chain Strategy

Used to deliver a series of solutions not one solution with different rates and volumes.

This strategy refers to the fact that the first pump is connected to your microscope and the foot switch input of the pump. Then a digital output of the first pump is then connected to the digital input of the second pump.

In this strategy the first pump delivers the first flow then sends a trigger signal to the second pump.

Pump TTL Db9 Connector

Pump TTL Db9 Connector

Connecting The Pump and Microscope

To control a pump from the microscope, owners arrange a digital signal line from the microscope to the digital inputs on the pump. This signal is then used by the program in the pump to stop/start flows or signal a change in rates. Think in terms of the microscope signaling the program in the pump to change the pump’s action – my software comes along for the ride monitoring your pump’s actions, as you develop your solution and as a monitor for operators when they use the microscope.

This is a simple plugs and cables issue. Identify your microscope’s digital output. Make sure its a ttl or logic signal style of output. 0-5Volts. Wire that to the pump’s foot switch input. Now all you need to do is work out whether your trigger signal is a rising or falling edge (the folks I talk too all have falling edges) – either way – you can configure the pump to deal with the different types of triggers.

Run Time Monitoring and Control of Pumps

This is where SyringePumpPro can talk to the pumps over the serial port (see I knew that would come up) and show you what the pumps are doing. You can also interrupt one or more pumps, or start and stop all the pumps synchronously using the RUN and STP buttons on the SyringePumpPro control panel.

What Problems Arise?

Watch out for pump communication problems – if your microscope is connected to the same PC we can see a little conflict between USB-RS232 adapters when more than one is used. Don’t rush to use PCI serial cards to solve that problem – again the cheaper cards don’t make your life any easier.

More than One USB-RS232 Device

This is common – the microscope or the camera already requires a USB-RS232 device, so we need a second one for the pump control circuit. Some and I must emphasize some, USB-RS232 devices come with driver software that sucks. They are usually purchased for bargain price. The driver software assumes that there will only ever be the one device, so plugging in a second device leads to one or more of them not working properly.

Confession: My SyringePumpPro also doesn’t help because it assumes that the first USB-RS232 device is where the pumps are – it’s only trying to help – really. So the trick here is to make sure that the pumps are on the first detected USB-RS232 device. The problem stems from first came the other device for the camera or microscope. Then along came the pumps and their second device.

Solution: Disconnect all USB-RS232 devices. Set up the pumps and SyringePumpPro. Now do the other device. Easy in the end!

Got a microscope related tip? Share it!!

Electro-spinning – High Voltage Protection 2018-02-08T23:02:15+00:00

The above diagram shows a layout for electro-spinning or electro-spraying. More details about the pump to PC interface cables.

Whilst I talk about electro-spinning in this post, my comments apply to electro-spraying too.

Taylor cone - Wikipedia

Taylor cone – Wikipedia

Electro-spinners use a very high voltage up to 50kV (at a low current) to attract a very fine threads from the needle of a syringe pump. The pump’s ability to provide very low flow rates combined with the high voltage allows the creation of new materials. Some of the applications are nano-fibres for protective clothing, ultra fine or specialist filters, medical drug applications, or to make materials for replacement body parts to name a few. It’s an exciting field indeed.

If you want to see state of the art electro-spinning equipment that uses SyringePumpPro, take a look at Spraybase equipment.

Best Electro Spinning Shielding Practices

  • Place the pump in a wire cage that is grounded
  • Make sure there is a mesh shield – larger than the pump – as large as the physical apparatus plus any reasonable airborne path back to the pump or other equipment.
  • Shield all cables, with their shield outer core connected to earth.
  • Distance is your friend – get the PC as far away from the high voltage as practical.
  • Don’t allow long data cables to roam the bench top and travel any where near the pump or spinning apparatus. Take all extra length to the PC end of your setup.
  • Make sure it is easy to shut off the High Voltage source in a safe and quick manner – don’t bury that power supply behind a bench full of other stuff.
  • Have a safety switch system to shut off the high voltage should an operator attempt to open the shielded enclosure containing the pump.

Electro-Spinners Can Destroy Equipment

Cable positioning and insulation are vital points in your apparatus construction. I have seen several customers destroy laptops, and pumps following an high voltage leak.

A poorly setup electro-spinning setup can leak high voltage into cables passing by – or from the syringe needle back through the pump.

Once the high voltage is in the  pump or the cables it seeks an earth connection and the only way to get to one is

  • Via the operator – if they are attached
  • the high voltage travels along the data cable connected to the pump, heads into the USB-RS232 adapter, up the data cable and into the PC and then along the to the pc power supply if it’s a laptop.
  • The high voltage may enter any cable that is not shielded.

The pumps fare better than the PC equipment

The pumps don’t seem to completely die instead they start doing weird stuff. They will work and then stop. They will communicate with SyringePumpPro and then stop. It can be hard to diagnose.

Laptops and PC do seem to die outright – they don’t take this kind of treatment lightly.

Operator Complacency Might be a Factor

One curious thing I have noted is that every time I am helping diagnose a situation where the high voltage has escaped I note:

The customer story usually sounds like this:

We have been electro-spinning for a few sessions now – after just getting going – they are past the initial get it going phase.

Our pump started miss-behaving a few sessions ago, and then it seemed all right for a couple of sessions and now it wont work at all – your software isn’t communicating with our pump.

We have tried re-installing your software but it didn’t help – re installation hasn’t ever fixed my software!

Now nothing is working.

I cant prove this – but I think we are seeing leaky high voltage escaping into the pump every now and then. I also suspect that as the operators get more comfortable, stuff moves around on the bench and perhaps a cable strays into the danger zone.

The pump chips do have limited electrostatic voltage protection – this is not a feature of the pump but a feature of all modern integrated circuits. So rather than the traditional zap – it’s dead, I think we are seeing a series of small zaps which wind up killing the chips protection circuits – then one more small? zap is all it takes.

Only once was I approached and a customer told me – I killed my laptop.

What I am trying to say here – is I think operators get an early subtle warning that the high voltage is escaping, and rather than one zap killing something, we have gear exposed to marginal conditions and being damaged.

Look for signs of problems and audit your electro-spinning setup regularly.

I am concerned about the high voltage safety side of things – I was given a shock whilst working on an aircraft radar transmitter. It was 30kV – not easily forgotten, I was quite lucky and didn’t suffer at all – but years later I still approach the high voltage stuff carefully – it JUMPS!

At WBC2016 World Biomaterials Congress in Montreal
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