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  • Writer's pictureTom Mueller

Penblog — José Luis Pérez Díaz of the Universidad de Alcalá on MELCHIOR, MESMERISE and more

My recent conversation with José Luis Pérez Díaz — the full podcast is here and here— ranged from EU Horizon funded projects Prof. Pérez Díaz has been involved with, in particular MELCHIOR, a Horizon 2020 funded project that aims to rapidly detect drugs, explosives, weapons and illicit goods that people have concealed on or inside themselves, using a range of novel and noncontact technologies.

It was a wide-ranging conversation, in which we also considered the challenges that Artificial Intelligence poses to human ethics, how you can “ring” bells and people to detect objects hidden on them, and why pigs are smarter than people (!)

This blog post summarizes the key points in our conversation, and provides some background materials on Prof. Pérez Díaz’s work.

Pérez Díaz’s background is in physics and mechanical engineering, and he has been working for the last three years in different security projects, related to space, nanotechnologies, decontamination. More recently he helped complete the MESMERISED project, and is now the project coordinator for MELCHIOR, related to border security and the detection of objects.

Pérez Díaz stresses the huge benefits of the multi-talented teams that projects like these bring together, and at the same time, the challenges of managing such a far-flung team, whose members often have different backgrounds, motivations, aims and even ways of discussing their work. “But most of time, you’re translating the language of one group of people into the other,” Pérez Díaz says. “Translating how the needs of end-users have to be transformed into prescriptions for engineers. Or vice versa: what is actually feasible, and can be implemented? This is the kind of work that the coordinator has to do. It's like an orchestra conductor.”


Pérez Díaz observes that the human body is something like a bell: If you attach an object to a bell, it doesn't ring the same way. By the same token, using sound waves you can detect objects concealed on or inside the human body, without an invasive pat-down, or creating an image of the person.

In MESMERISE, Pérez Díaz and his team developed two different technologies. The first was X-ray transmission scattering with an ultra-low dose, which they tested on pig carcasses and human cadavers, to determine the sensitivity for detection of drug balls in the digestive tract. The second technology was infrasound, without ionizing radiation or other harmful technologies. The team demonstrated that the scattering of this low frequency sound in a particular way could be useful for the detection of concealed items under clothing (eg explosives, weapons, etc).


MELCHIOR is a classic case of a public-private partnership, used effective to drive innovation. The EU funds public and non-profit institutions at 100%, but funds private enterprises at 70% — these entities pay the remaining 30%, which ensures their strong commitment to the project.

Pérez Díaz noted that he and his fellow members of the MELCHIOR consortium sometimes derive inspirations for their work while traveling. They become “guinea pigs” for search methods, and sometimes have new ideas.

He notes that major benefits for customs administrations from the MELCHIOR project include:

  • Customs officers doing security checks would avoid touching somebody who might be wearing an explosive belt or other dangerous device.

  • Personal searches become more relaxed for both the passenger and the officer, by avoiding awkward pat downs.

  • MELCHIOR tools increase the flow of people, with a relatively high rate of reliability, making customs procedures smoother and simpler.

Further potential applications for MELCHIOR technology include use in correctional facilities, football stadiums and concert halls, and other contexts where you need to prevent people from carrying guns or explosives. .

Pérez Díaz noted that artificial intelligence can help customs officers, because machines never get tired or lose their accuracy: AI is a tool that we can use to help the user, the human. But at the end of the day, he notes, “Human beings must always lead the process. The final decision must be a human decision.”

The conversation concluded with an interesting discussion of how AI can potentially clash with human ethics, and what we need to do to ensure that technology remains guided by human beings and human ethics. Speaking about AI, Pérez Díaz said, “You can use it for goodness, or for evil. If you use it for evil, to control people and to know more about them than you know about yourself, I think we’re following the wrong path. But if we use it as a tool, to identify things quicker and to analyze a complex amount of data to detect something that is concealed, then that’s good.”

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