This week marks the fifth anniversary of 7/7 bombings, when four suicide bombers from West Yorkshire detonated explosive devices at Aldgate and Edgware Road underground stations, and on the Piccadilly Line between King’s Cross and Russell Square.

A further device was exploded on a double-decker bus at Tavistock Square in central London, and a total of 52 people lost their lives.

Since those events, The Engineer has reported on several anti-terror technologies that demonstrate how technology can be further evolved used to safeguard us and the nation’s infrastructure.

Despite the many advances, a considerable number of you wrote in to question the practicalities of deploying certain devices and whether indeed they pose a threat to individual liberty.

Questions about practicality were raised on May 12 2010 when The Engineer reported on the LOTUS (Localisation of threat substances in urban society) project.

The €4.3m project aims to develop a mobile sensing technology that can detect whether homemade bombs are being made in urban environments.

Dr Henric Östmark, head of LOTUS’ steering committee, said initial sensors will be sensitive to hydrogen peroxide, which was the main chemical used in the 7/7 bombs. Read more about LOTUS, and the questions raised about its deployment, by clicking here.

In Turkey, Resat Apak and colleagues from Istanbul University are developing a sensor sensitive to peroxide-based explosives, such as triacetone triperoxide (TATP) and hexamethylenetetramine (HMTD).

Apak’s colorimetric sensor selectively detects the peroxide-based explosives TATP and (HMTD) and is claimed to be ideal for post-blast analysis and identifying unknown materials or suspect packages confiscated by the police.

Air travel and security had many of you writing in after the publication on March 22 of a report about how Smiths Detection had demonstrated the 16HR-LD model of its B-Scan technology.

The transmission X-ray scanner is claimed to be the first low-dose security technology that is able to see all internal body cavities for thedetection of concealed threatening objects, such as bombs and detonators. Questions concerning ionising radiation were clearly foremost among you. Read more here.

Finally, a story broken by The Engineer that was met with a degree of incredulity involved the development of a sensor to detect a person’s fear, the theory being that a person about to commit a terrorist act gives off a certain chemical signature.

On October 26, 2009 The Engineer reported how the device could identify terrorists during routine security checks at airports and high-profile events.

The technology was the subject of a study being undertaken by City University London with support from the Home Office Scientific Development Branch.

Led by Prof Tong Sun, the 18-month project aims to develop two sensor systems that can detect the unique chemical signature of the fear pheromone, assessing the stress of an individual and interpreting it in security-critical contexts.

The first device is expected to be based on laser absorption while a further area of research would look at the development of a portable optical-fibre device. The news story can be read here.

Can technology provide us with safeguards or does a more holistic approach to security need to be adopted? Let us know your thoughts.