Inventor: Robert Simpson

Download the Executive Summary

A new look at the simple door security chain. By utilizing knowledge gained through the development of the auto access control RDS Innovations has now developed and patented this device.

A door chain does not provide evidence of an attack. This device does.

Installed at an entry point around your home, when in use if attacked will automatically sound a high decibel alarm to alert neighbors and passers-by but at the same time sprays the attacker with a TOTALLY NON-TOXIC UV based forensic marking fluid. This stain remains for weeks and is easily identified by police using simple UV (CSI) torches. Or if the attacker frequents premises that use UV lighting such as night clubs and bars the spatter is clearly visible.

The forensic evidence collected by police forces, and other law enforcement agencies once analyzed puts the intruder at the scene of THEIR crime. As the device can only be activated by definitively attacking the door, there is a clear chain of evidence.

The device is currently installed by a registered installer network here in the UK ensuring that all unique DNA trace information is held on a conforming national database which is available to police authorities.

Once the unique forensic component is identified this information can be used to identify the door it was registered to, and this forensic evidence can be used by law enforcement to track a criminal back to a specific crime scene anywhere in the world.

License Available

Please contact RDS for more information.

Development to Date

2009 – 13

  • StranDNA (UK) Limited was established by myself to supply, install and forensically register what was given the name “Chain Reaction DNA”.
  • 1000 units were manufactured
  • Demonstrations and further information provided to security organisations globally.
  • The Society Of Professional Locksmiths (SOPL) based in the USA award and recognise Chain Reaction DNA as a product of value.
  • Chain Reaction DNA receives Sold Secure Status from the Master Locksmiths Association shortly followed by Secured By Design as an official Police crime reduction initiative.
  • Interest received from the world largest suppliers of forensic based security products.
  • Tetrafluoroethane was used as an evacuant but during trials it caused the liquid to freeze on dispersal.

2013 – 2015

  • Work with Police forces nationally in a number of safeguarding applications including domestic violence (DV)), Asian gold theft, repeat victims of burglary, witness protection, Gender hate, Race hate, honour based violence (HBV), elderly/vulnerable victims of crime, so to ease their fear of crime.


  • StranDNA (UK) Limited was acquired by The Avocet Hardware Group and the intellectual property, prior art regarding the reinvention of the door security chain was re-licensed.
  • The product was rebranded and became A.I.M (Avocet Intruder Management)
  • I was retained as a “Forensic Alarm Advisor” and continued to assist Avocet Hardware to the best of my ability and informed them that the use of tetrafluoroethane was going to be restricted and therefore a new deployment system was required.

Download the Avocet Executive Summary

Download the Avocet Installation Process

2015 – 2022

  • RDS Innovations Limited were made assurances which were not followed through so therefore the License was rescinded. (NDA required for details)


  • Since the banning of tetrafluoroethane I have been developing a new way to make the product slimmer, battery powered, to include impact camera and the capability to deploy any type of UV based forensic trace available on the market today.
  • Independently assessed by as a commercially viable product based on development to date.
  • Independently assessed by the MTC Technology Readiness Level 9.


  • Officially announced as a finalist by the Great British Entrepreneur Awards in the category Innovation Entrepreneur of the Year 2023 regarding “Forensic Chain Of Evidence”.
  • This award recognises individuals who have demonstrated exceptional creativity, originality, and entrepreneurial spirit in their pursuit of new ideas and innovative solutions. Nominees for this award will have shown a willingness to challenge conventional thinking and to disrupt established business models, leading to significant changes and advancements in their respective industries.

Contact RDS Innovations for further information