Syringe Pump

What are Syringe Pumps?

Syringe pumps are built around a motor that can either insert or retract a plunger from a syringe. By knowing the internal diameter of the syringe and the distance moved by the motor, the volume and rate at which a solution is moved can be calculated. The video on the right shows how a single pump can be used to either continuously infuse or withdraw a liquid, or provide a pulsed flow.

When two syringes are controlled, a wider range of experimental setups can be used. An example of the precise mixing of two different solutions is shown below. This can allow for accurate control of chemical reactions in processes such as microfluidics. In addition, this process can be used for producing emulsions of two immiscible solutions. When combined with equipment such as check valves and solvent reservoirs the pump can be used for continuous pumping of a single solution.

How do Syringe Pumps Work?

Syringe pumps feature stepper motors which can accurately move a platform attached to the plunger of a syringe. The body of the syringe is held steady to the body of the unit so that the only movement is from the action of the motor.

The onboard computer allows the motion of the stepper motor to be programmed. The Ossila Syringe Pump provides a straight-forward and self-contained system, through which each individual step of the motor can be controlled. When two syringes are used (on the dual pump model) each can be programmed and operated completely independently of the other.

What are the Different Types of Syringe Pump?

There are two main types of syringe pump: those designed for medical use and those designed for use in a lab. Although they share the same name and perform similar functions, the two should not be confused.

Medical syringe pumps are approved for use by medical professionals in the treatment and care of patients, typically in facilities such as hospitals and care homes. They are closely related to infusion pumps but administer treatment from a syringe rather than an intravenous bag. Compared to infusion pumps, syringe drivers control the flow of much smaller doses of medication. They are often used in palliative care.

The degree of precision and amount of control provided by medical syringe pumps is generally less than that provided by scientific syringe pumps. Instead, medical syringe drivers come with drug specific pre-sets and pre-programmed hard and soft limits designed to ensure the safety of the patient.

It is important to note that scientific syringe pumps are not interchangeable with those designed and manufactured specifically for use in vivo. Our syringe pumps are for laboratory use only.

Syringe Pump Hardware Specifications

In-built Software Specifications

Maximum and Minimum Flow Rates

The maximum and minimum flow rates of the syringe pump is determined by both the stepping rate of the motor driving the syringe and the diameter of the syringe in use. For different volume syringes the maximum and minimum flow rates for the system will vary, below is a table that quickly summarises the flow rates achievable with different syringe sizes.

As can be seen in the table by choosing the correct syringe diameter it is possible to achieve a range of dispense rates spanning 8 orders of magnitude.

Dispense Rate Accuracy

Just like the maximum and minimum dispense rates, the accuracy of dispensing depends on the accuracy of both the syringe pump and the syringe being used. The Ossila Syringe Pump has a stepping accuracy of 0.16% which gives a rate accuracy of 19 nm.s^-1. However different syringes will have manufacturing tolerances on the internal diameter, the type of syringe used therefore will have a strong impact on the accuracy of flow rates.

Plastic disposable syringes commonly used due to their ease have the lowest tolerances with diameters that can vary by up to 3% depending upon the manufacturer, this can result in up to a 6% error in your dispense rate. Glass and stainless steel syringes have a higher tolerance with a maximum of 0.5% variation in the internal diameter, this results in a volume error of up to 1%.

Maximum Force Limitations

The maximum applicable force can be varied in the system for use as an additional safety feature. At its maximum the pump can apply over 500N of linear force to the syringe. For a 50ml syringe this equates to a pressure of 4.37 bar placed upon the piston, while for a 5ml syringe this becomes as high as 47 bar.

Most syringes are rated up to a certain maximum pressure, for plastic syringes this is 10 bar, glass syringes this can be as low as 1.5 bar or as high as 30 bar depending upon the make. Therefore setting maximum limitations within the software based upon the syringe manufacturers recommendations protects your syringes against damage.

In-built Software

The Ossila Syringe Pump has been designed to be a completely self-contained unit so no external controls are required in order to operate the system.

Ossila's intuitive syringe pump software allows for the easy programming of complex multi-step experiments without needing to connect it to an external computer or laptop. The software can save and store up to 20 different programs to the unit's in-built memory, each with a total of 100 individual steps. This allows for the programming of complex processes, such as sequential deposition of multilayered structures. Each step allows the user to select a dispense rate, a dispense time, and/or a dispense volume.

Combining a colour LCD display, easy-to-use touch pad, and intuitive user interface allows for rapid navigation through the options and settings. This lets you set up and run new experiments quickly and easily.

You are able to set the syringe size either from a range of preset sizes, or by entering a custom size. Additionally, the maximum force provided can be controlled, allowing the user to protect glass syringes from potential damage. A manual mode has also been added, allowing the position of the syringe pump to be set up quickly for faster loading and unloading of syringes.

Getting Started with the Ossila Syringe Pump

With no external dependencies, the Ossila Syringe Pump is quick and easy to set up and use.

Begin by placing it on a flat and solid surface away from vibrations, temperature extremes and hazardous materials. Ensure that the unit is switched off, connect the power supply to the mains outlet, plug the power cable into the unit, and turn the syringe pump on. When booted, the LCD display will show the 'setting mode' screen.

From the 'setting mode' screen, you can set the force and select the diameter of syringe that you will be using. The most common sizes (1ml, 2ml, 5ml, 10ml, and 50ml) are pre-set, but you can also enter a custom diameter.

Pressing the manual button will switch the syringe pump to manual mode. Manual mode allows you to move the plunger forwards and backwards by pressing the forwards and backwards buttons on the front panel of the unit. This is particularly useful when attaching a syringe (see below).

Alternatively, pressing the program button will allow you to set up a routine or run a pre-saved program. Solution dispense volume, rate and time can be controlled at each step and the dual pump model allows for each pump to be programmed independently of the other. When you are satisfied with your program, just press START to run the sequence and the pump will operate automatically.

More information on how to operate the Ossila Syringe Pump, including step-by-step instructions on how to create a program using the in-built software, is available in the Syringe Pump product manual. Please ensure that you have read this before setting up or operating your Syringe Pump.

Attaching a Syringe to the System

Attaching a syringe to the Ossila Syringe Pump is straight-forward.

1. First, pe-load the syringe with your solution. Make sure that there are no air bubbles before proceeding.
2. Place the barrel of the syringe into the groove on the syringe holder, with the top inside the clamping mechanism. You can then lower the clamping arm onto the top of the syringe and lock it into place by tightening the wing nut.
3. Enter manual mode on the syringe and drive the plunger holder until it rests against the end of the plunger. Once in place, tighten the clamping mechanism around the plunger. This should be parallel with the barrel of the syringe.
4. Connect any additional tubing or fixtures required for your experiment, using manual mode to preload the fixtures and tubing with your solution.

Please see the product manual for more information.

Syringe Compatability

The Ossila Syringe Pump is fully compatible with the Ossila Spin Coater. The Spin Coater and Syringe Pump package includes both pieces of equipment at a discounted price plus a FREE connection adapter, disposable syringes, PTFE tubing and needles.

The Ossila Syringe Pump is compatible with a range of syringes, including:

Connecting the Ossila Syringe Pump to the Ossila Spin Coater

The exit of the syringe can be connected to the Ossila Spin Coater via the use of PTFE tubing with connector/socket Luer lock adapters fitted at the ends. The diameter and length of the tubing used is dependent upon the total volume of solution you have as well as the viscosity of the solution. For highly viscous solutions we recommend a wider diameter pipe to maintain a lower overall pressure within the system.

At the exit of the tubing, we recommend using a blunt needle with a Luer lock adapter for the actual dispensing of solution into the spin coater. By selecting a specific gauge of needle the minimum droplet size can be varied for your experimental needs. The blunt ending also reduces the chances of injury or damage to equipment if used within a glovebox.

The ends of the needles can be positioned directly above the spin coater entrance by using clamps or other similar equipment. Alternatively a rubber stopper with a single hole in the middle can be used to hold the needle in position, we recommend a stopper size of 0 or 1 for the Ossila spin coater to get a tight fit within the lids hole.

The Syringe Pump and Spin Coater bundle includes disposable syringes and needles plus a free connection adapter and a length of PTFE tubing.

Preventing Solution Dripping after the Syringe Pump has Stopped

When auto dispensing solvents, droplets are sometimes dispensed after the syringe pump has stopped. The cause of solution dripping can be due to several factors, including: the syringe type being used, the presence of air bubbles, the viscosity of the solution, the density of solution, and the surface tension.

The most common cause of this occurrence is when a pressure difference between the inside of the syringe and the outside remains after the solution has been dispensed. This can happen when air bubbles are trapped inside the solution, resulting in a compression of the gasses during dispensing. After the pump has stopped, the compressed air expands and pushes solution out of the syringe. Similarly, for plastic syringes and pipes, elastic deformation. Over time, this can result in dripping of the solution.

This can be avoided by removing bubbles within the syringe before loading, using tubing and syringes that show limited amounts of elastic deformation, and reducing the overall pressures within the syringe. To avoid a build-up build up in the syringe lower dispense rates should be used, the viscosity of solution can be reduced, or the velocity of the solution can be reduced by increasing the diameter of pipes and needles.

Sometimes, dripping can be due to the use of dense solutions with low surface tensions and viscosities. The adhesive forces between i) the molecules in the solution, and ii) the surface of the needle and tubing can become lower than the gravitational force acting upon the solution within the tube. This results in the continuous dripping of solution, until the gravitational force acting on the solution in the tubing becomes lower than the combined adhesive forces of the solution and the increasing pressure difference due to the displaced volume.

To reduce the effects of dripping from dense, low surface tension solutions, a lower diameter of tubing and needles should be used. Alternatively, the tubing and needle can be tilted horizontally to reduce the gravitational force being exerted in the direction of the tubing.