If you’d like to find out more about the types of cryogenic design and engineering projects which we currently carry out, then have a read through some of our case studies and product profiles. We have highlighted particular projects and products from our experience which we thought would be of most interest to anyone who’d like to find out about our work.
Designing and manufacturing cryosurgical probe stems
Nu Perspectives specialises in the design and manufacture of cryosurgical probe tips for clinical applications ranging from ophthalmology to pain management. These products develop extremely low temperatures at the tip via the circulation of high pressure cryogenic gases.
We are highly experienced in the manipulation and welding of thin walled hypodermic tubes and we use this knowledge to produce very innovative design solutions. These products are carefully engineered to provide specific tip shapes and profiles that are matched to our customers particular clinical applications and precision manufacturing is required to ensure that pressure and flow characteristics are optimised. Probe stems are designed to safely withstand extreme conditions in terms of internal pressure and temperature.
In order to assure product quality and safety probe stems are pressure tested in-house using specially design fixtures to several times their normal operating pressure.
Traditionally these items have been incorporated into reusable medical products and materials have been carefully selected to withstand many sterilisation cycles. Nu Perspectives has also developed probe stems for disposable devices which have lower manufacturing cost but still need to meet very exacting safety and reliability requirements.
Reducing costs to produce a new probe connection system
We were approached to develop an intuitive, easy to operate mechanism for connecting and disconnecting a range of reusable and disposable cryosurgical probes to and from the control console for a leading ophthalmic cryosurgical system. The client wanted a simple, elegant and safe system as well as to reduce the manufacturing cost of the overall system. This required a change to the coupling for reusable cryogenic probes and a completely new quick release connection mechanism for the console.
Nu Perspectives worked very closely with the customer to specify the exact functional requirements and cost reduction targets. We had to work within very specific regulatory parameters as it is a medical device.
A simple and safe probe coupling mechanism for the control console was designed which worked within the existing space, requiring no changes to the existing moulded system. A new and simplified probe recognition system only required small changes to the electronic system and control software.
We worked with the customer to identify other potential cost saving opportunities which could be exploited either by design change, process simplification or other operational means.
Creating a brand new cryo device for pain management
We were approached to design and develop a new medical device for cryotherapy and pain management. It involved combining nerve stimulation and cryotherapeutic technologies within a single revolutionary medical device.
Nu Perspectives worked to develop an autonomous cryo module which would then be housed within the main enclosure and controlled from the computer via a USB interface. The cryogenic functions and safety interlocking were controlled via a dedicated embedded system.
We also developed specialised pain management cryoprobes which provide accurate nerve stimulation together with the cryotherapy. These probes were carefully engineered to produce consistently excellent clinical outcomes.
On completion of the project we continue to work closely with our customer providing turnkey production manufacture and product support for all their cryo requirements.
Designing modular pneumatic control systems
Nu Perspectives is experienced in the design and manufacture of modular control systems for various pneumatic applications with pressures ranging from a few PSI to over 100 bar.
Using the latest 3D CAD, we are able to develop compact manifolds which provide the necessary fluidic paths whilst aiming to reduce the internal machining to a minimum. Mounting pneumatic components like solenoid valves, pressure and flow sensors directly to the surface to the manifold makes assembly and servicing much simpler by eliminating more traditional 'piped' interconnections.
Nu Perspectives is highly skilled in the specification of sealing methods for both static and dynamic applications.
Using microprocessor systems designed in-house, Nu Perspectives is able to implement novel control schemes in order to control gas pressure and flow for a variety of applications.
How we used reverse engineering to create a part for a legacy cryosurgery probe
At Nu Perspectives we pride ourselves on having in-house manufacturing capability and this came to the fore when a customer approached us to supply a spare part for a legacy cryosurgery probe. The part was no longer available from the original manufacturer but our customer was still using the probes and need to support their own clients who had this product in use out in the field.
It was a very bespoke part which incorporated several different technologies and a variety of manufacturing processes, which is why they were struggling to find one. Creating it required experience in design, manufacture and outsourcing of machined parts, thermocouples, o ring seals, assembly, brazing, soldering and pressure testing – all of which we could help with.
The part also needed to be designed so that it would always work with the existing parts so we needed to give true consideration to tolerances. We used Solidworks 3D CAD to reverse engineer the parts. We had the necessary experience and technology in house to successfully design and manufacture this spare part for the customer, enabling them to continue to support their clients.
Bespoke repair for a legacy cryogenic product
Doctors from a hospital were still using an old legacy cryogenic surgical product which was working okay but they contacted the Nu Perspectives team to see if we could test and service the product to make sure it was still working at its optimum and to check it over.
It was an old product but from a brand which we had worked with in the past and we knew the manufacturer no longer existed. We took the surgical system to our premises and ran several tests which revealed that while it was still working there were some faults.
We disassembled the product and found a split hose and several valve leaks, so we completely cleaned out the whole system, replaced all the hoses and all the seals, as well as some springs, before putting it all back together.
Our team then retested the equipment after reassembly, to make sure it was all now working perfectly, before returning it to the hospital to continue to use it for patients. At Nu Perspectives we have our own in-house testing and manufacturing facility which means we are easily able to carry out tests and repairs on products directly ourselves, even if they are legacy systems.
Cryogenic instruments for probe stem assembly
At Nu Perspectives we pride ourselves on finding bespoke solutions to cryogenic system problems in house thanks to our precision engineering skills – and we are constantly looking for ways to improve our processes.
We manufacture cryogenic instruments in-house and one of the items we produce for probe stem assembly required a time-consuming and labour intensive gluing process which we decided needed improving and streamlining.
Previously, the process involved applying glue to a tube, then pushing a glue collar on over the glue. The collar had to be worked into position while applying glue and unfortunately this was creating excess glue, was highly time-consuming and not as efficient as we needed it to be.
So we decided to change the process by creating some new bespoke tools ourselves. We created a tool to hold the parts in place which allowed us to then directly inject the glue into the right place – it means we can inject the glue straight into the void between the stem and glue collar reducing any glue mess and making the whole process much quicker.
At Nu Perspectives we are always looking for efficient ways to solve cryogenic manufacturing and production issues in-house, and in this case, creating our own tools has speeded up the assembly time and ensured we get consistent results every time.
Service and repair of legacy cryosurgical devices
Cryosurgical devices are subjected to extremes of temperature and internal pressures whilst in use and during routine sterilisation and cleaning. Internal components are prone to wear and tear and require replacement periodically.
Many of our customers' favourite cryosurgical devices are no longer supported by the original manufacturer. These older devices work perfectly well and provide the users with familiarity, as well as excellent and predictable clinical outcomes for their patients. Therefore, fixing a device, as opposed to replacing it, is sometimes preferable.
Our experienced engineers are able to service and repair many types of legacy systems, both gas based and liquid nitrogen based. We see a wide variety of cryosurgical systems where the original manufacturer has long since disappeared: the Spembly Portable Cryo Gun (PCG), Cryopac Consoles and Probes, Lloyd Neurostat and Probes, various handheld liquid nitrogen sprays, to name but a few.
Nu Perspectives hold stocks of many common spare parts and, if necessary, we can re-manufacture more specialised or custom components to ensure these systems can perform reliably and safely for many years to come.
Specifying correct orifice sizes for gas based cryosurgical probes
Gas based cryosurgical probes use the Joule-Thomson (JT) effect to achieve rapid freezing at the probe tip. The JT effect is a thermodynamic process that occurs when high pressure gas is flowed through a small orifice into a large chamber, causing a pressure drop. Cryogenic gases such as Carbon Dioxide or Nitrous Oxide cool rapidly when this process is applied.
The JT effect has been used for many years in Cryosurgical medical probes, and is an effective way of producing temperatures in the region of -70 Deg C. The cooling process is almost instant and the defrost is just as quick, which makes it good for procedures where several short freeze cycles are required.
The shape of the JT orifice is important in achieving consistent and reliable performance, generally the orifice shape will be circular or annular. The annular orifice is susceptible to changes in flow rate as the orifice size can vary as the internal parts contract due to cooling. An additional problem is that they are very susceptible to blocking either by debris or moisture. The width of the annular orifice is only a few microns so any particle sizes larger than this will block it. Whereas, the hole diameter is much larger than the width of the annular gap so much larger particles can pass through it. The hole is also less susceptible to variation in size due to cooling.
Setting the flow rate level is critical to getting the best performance out of the probes, in terms of freeze temperature, ice growth, reliability and avoiding unwanted freezing. The flow rate required will be dependent on the type of gas, the system design and size of the probe.
We have carried out extensive testing in order to characterise the anticipated flow rates for different pressures and systems. From this we are able to predict the hole size needed to supply the desired flow rate for each particular application. We have found that a difference of 0.01mm in diameter can make as much as 1ltr/min difference in flow rate. Therefore, we require precision nozzles to set the flow rate which have long lead-times and large minimum order quantities. Having a high degree of confidence that the nozzle size chosen will deliver the desired flow rate reduces costs and lead-times of projects.