Defence and Security Accelerator assists innovation in saving spilled blood

The HemoSep system

Assisted by the Defence and Security Accelerator, the HemoSep system was developed at Strathclyde University and has now been licensed to Advancis Surgical, a medicine-focused part of Nottingham-based engineering and research company Brightwake, which is manufacturing the device in the UK and marketing it worldwide.

HemoSep springs from research led by biomedical engineer Prof Terry Gourlay between 2008 and 2013. The key to the system is a special blood bag that contains filters to remove harmful substances from spilled blood while letting through the oxygen-carrying red cells, infection-fighting white cells, and the platelets and proteins that make up the vital mechanisms of blood clotting. The bag also contains an absorbent pad that soaks up excess plasma that has diluted the blood, locking it into a harmless gel form for easy disposal. The reconcentrated blood is then suitable for transfusion back into the patient.

Autotransfusion has many advantages. It reduces the need for medical facilities to keep such large stocks of donated blood on hand for emergencies; it completely removes the risk of rejection of donated blood, as the patient’s own blood is used and compatibility is therefore guaranteed; it is also suitable for patients whose religious beliefs prohibit transfusion from donors. Although autotransfusion has been used for some years during open-heart surgery, it has relied on complex machinery using centrifuges and pumps that need to be operated by specialist technicians.

A funding call from the military spurred the research on, and led to the development of the commercial version that had been successfully used in an operation to repair the aorta of a patient suffering from the connective tissue disease Marfan syndrome, but who as a Jehovah’s Witness could not receive a donor transfusion.

Conical rotors for compressors

Rob Solly, acting head of the Defence and Security Accelerator, said: “A company called Vert Rotors came to one of our face-to-face meetings, and we said its conical rotors for compressors could be used in satellites and gave it a small grant; it then used that to help raise £1.5m, which it has invested in machinery to help it grow its capacity and capability. It was also having difficulty getting funding for the business governance side, which is something that small businesses don’t necessarily have any expertise in.”

This can be a big problem for SMEs working with defence, he added. “There’s phasing that needs to happen here. If you’re buying a warship there are strict stages of requirements, that all the parties understand; but if you’re applying that to an idea that’s only just getting off the ground, there’s a real danger of snuffing it out. You need to be slightly more agile in requirements.”

Compressors are a vital piece of equipment in many industries; compression of gases is very common for many processes. But many versions of compressor technology tend to create vibration, which can be a problem, for example, in space and medical applications. Screw compressors are a low-vibration option, but they tend to be large (above 2kW) so are not suitable for all applications.

Edinburgh-based Vert Rotors has developed a version of the screw compressor that can deliver vibration-free compression at low volumes. First demonstrated in 2013, it uses a single cone-shaped inner screw in a similarly shaped housing to perform gas compression, rather than the two cylindrical screws side-by-side of a conventional screw compressor. In a traditional system, the clearance between the two screws and their housing allows gases to leak back, reducing efficiency; the conical compressor system eliminates this problem, producing 30 per cent  better energy efficiency, the company claims.

The compressor works by trapping air between the inner and outer rotors, with intake at the wider end. As both rotors revolve, the air is forced down to the narrow end, and as the space between the rotors decreases pressure is progressively increased. The size of these compressors is 100 to 1,000W.