Most fingerprint scanners work the same way – the pad of the finger is pressed against the scanner’s glass surface, light is shone through the glass onto it, and the light that’s reflected back by the minuscule valleys between the print’s ridges is used to create an image of the print. It’s a system that’s usually effective, although it can fail to read prints that have been flattened by age or damaged, plus it can be fooled by gelatine casts of fingerprints. That’s why scientists from the Paris-based Langevin Institute have developed a more reliable scanner, that looks below the skin’s surface.
Created by postdoctoral researcher Egidijus Auksorius and Prof. Claude Boccara, the scanner utilizes a technique known as optical coherence tomography (OCT). This is already used in medical imaging, and involves analyzing the interference pattern that occurs when two beams of light are combined – one of those beams serves as a reference, while the other is shone through a biological sample.
In this way, the scanner can image the “internal fingerprint” located about half a millimeter below the surface of the skin, which has a pattern identical to that on the outside – except it’s unscathed.
Images acquired using the new technology, which also images sweat ducts
While existing OCT machines are relatively big and expensive, the scientists are using a more compact version of the technology called full-field OCT (FF-OCT). As a result, their scanner is currently about the size of a shoebox, although they’re working on making it smaller, faster-operating and able to scan deeper. Its most expensive component is a US$40,000 specialized infrared camera, although they’ve recently had success using a camera worth about one-fifth as much.
Ultimately, they hope to produce a finished product that could be made for just under $10,000. This means that it won’t likely be finding its way into consumer products anytime soon, but would instead be utilized in settings where security is particularly important. That said, scientists at the University of California, Davis and Berkeley are working on an ultrasound-based 3D fingerprint reader that could replace capacitive scanners on mobile devices.
Plans call for the Langevin device to be field-tested on 100 individuals, in Turkey. A paper on the research was recently published in the journal Biomedical Optics Express.
Using Dr Liang’s method the prints glow under UV-light and different colours can be achieved by altering the chemistry. Photo: CSIRO
After CSIRO scientist Dr Kang Liang’s house was broken into, he developed a new fingerprinting technique to catch the bad guys.Vision: CSIRO.
It’s a storyline straight out of CSI Australia.
A young scientist has his home broken into but police can’t find any fingerprints at the scene.
Rather than give up in despair, Dr Kang Liang uses his awesome science powers to develop a new technique that will allow forensics to better capture fingerprints and make them glow at the scene of the crime.
Dr Kang Liang of CSIRO. Photo: Eddie Jim
And while it’s too late to solve his case, by spurring on the CSIRO scientist, the foolish burglar probably did a grave disservice to criminals everywhere.
Materials scientist Dr Liang is now savouring the sweet taste of revenge.
His research, published in the journal Materials Science this week, will allow for forensic police to “dust” for prints using a drop of liquid containing luminescent crystals. Applied to fingerprints, the crystals create a greater contrast between the mark left by a criminal and the surface enabling higher resolution images to be taken for easier and more precise analyses.
The crystals attach themselves to the proteins and peptides of the fingerprint residue and glow under ultraviolet light, making detection even easier.
“While police and forensics experts use a range of different techniques, sometimes in complex cases evidence needs to be sent off to a lab where heat and vacuum treatment is applied,” Dr Liang said.
“Our method reduces these steps, and because it’s done on the spot, a digital device could be used at the scene to capture images of the glowing prints to run through the database in real time.”
“When my house was broken into, and knowing that dusting has been around for a long time, I was inspired to see how new innovative materials could be applied to create even better results,” Dr Liang said.
“As far as we know, it’s the first time that these extremely porous metal organic framework crystals have been researched for forensics.”
The CSIRO is now looking to partner with police forces around the country
A new technology will allow authorities to tell whether you used drugs recently, if you’re a smoker, even what sex you are—all from your fingerprints.
In 2010, a North Carolina woman was found on the side of a roadway, brutally murdered. At first the Guilford County Sheriff’s Department had no suspects, but they knew from witness testimony two key facts: that the victim was last seen with a man, and that a baby seat in the back of the car had been removed during a struggle.
When they found the car seat and powdered it for fingerprints, there were prints all over it. The problem? The fingerprints came from at least two different people: the person who they believed may have committed the crime and someone who had nothing to do with it. No hits for either print came up in the FBI’s national fingerprint database, called IAFIS (Integrated Automated Fingerprint Identification System).
But imagine if there were more to fingerprint science than running patterns of whorls through a database. Picture forensic investigators using fingerprints to find out whether the person who left them was a smoker, whether they had recently handled drugs or explosives, or even to determine their gender.
“We had a suspicion the suspect was a guy, because people had seen the victim with someone. If we knew early on how to eliminate the female prints, we could have just focused on the male prints,” said Sgt. Patricia Wisneski, crime scene investigative unit manager for the Guilford County Sheriff’s Office in Greensboro. While the man in the murder case was eventually arrested, officers might have found him a lot faster if they’d been able to analyze fingerprints this way.
Now, they are. The Guilford County Sheriff’s Department is one of several law enforcement agencies testing a new fingerprint technology that can analyze metabolites left behind in fingerprint residue for a variety of factors. The ability to eliminate certain crime scene prints from the start enables investigators to send out fewer samples to be tested for DNA, which can be a costly and time-consuming process, Wisneski said. Knowing whether the person had handled drugs or explosives doesn’t hurt, either.
“Knowing any additional information about a suspect is always helpful and can generally lead the detectives in the right direction earlier in an investigation. Obtaining information sooner is always better than later,” Wisneski said.
What Your Fingers Tell About You
The technology, created by ArroGen Group, a forensic solutions company based in Greenville, North Carolina and Newcastle, U.K., uses a powder that contains sub-micron particles that adhere to the amino and fatty acids in fingerprint residue. While scientists have long used powders to develop fingerprints, these new materials produce images with higher contrast, better clarity, and less background staining.
The Fingerprint Molecular Identification (FMID) process, as the company calls it, works like this: Scientists sprinkle the powder on the print at the crime scene, then remove it from the crime scene using lift tape. The samples are sealed and brought to the lab, where they are put into a mass spectrometer that scans the print with a laser. As the machine pans the surface, it vaporizes and ionizes the particles in the powder and molecules in the fingerprint residue, enabling the machine to detect molecular profiles in the residue.
Depending on the level of compounds in the secretions left in the print, the machine can detect not only the sex of the person but whether whomever left the print had consumed drugs like cocaine, marijuana, heroin, or methamphetamine; smoked or chewed nicotine; or had touched a gun or explosives. What’s more, ArroGen says they can detect all this information up to a month after a fingerprint has been left—and they’re testing for the ability to read read prints left as long as a year ago.
“The engineered particle powders provide higher contrast and clarity when developing latent fingerprints, and allow for the collection of molecular information when coupled with mass spectrometry,” says Kim Sandquist, chief science officer of chemistry at ArroGen.
Prints lifted with this powder have a greater sensitivity when analyzed with the mass spectrometer, meaning that it picks up more data and smaller amounts of drugs or other biomarkers. Sensitivity can make the difference between getting a result and not getting a result, especially when you’re working with minuscule amounts of material.
Still, ArroGen is being intentionally cagey about how exactly they determine all this information from just a fingerprint, beyond saying that your fingerprints include “hundreds of molecules, including but not limited to fatty acids, amino acids, and lipids.”
One of Sgt. Wisneski’s great frustrations is seeing prints that she knows (or strongly suspects) are from the suspect, like fingerprints left on a glass window when someone pushed it up to break into a house, yet the print is unusable because a portion is smudged. It happens a lot, especially because many substances, such as the plastic gas containers often used in arsons, are not good for capturing useful prints, she said.
“Certain plastics break up the ridge flow,” Wisneski said. “You might see finger marks were someone touched it, but there’s just no ridge detail to be collected because of the surface it was left on.”
ArroGen hopes it could fill the missing details in smudged fingerprints by following the chemical residue left behind and then mapping out where it is. A high-resolution image could then be reproduced. For now, ArroGen doesn’t advertise that as one of the product’s features, but it could be coming next year, Sandquist said.
What You Leave Behind
Mark Dale, ArroGen’s Chief Operations Officer, likes to cite the concept in forensic science called the Locard Principle, named after the French criminologist Edmond Locard, who said every perpetrator of a crime brings something into the crime scene and leaves with something from it. When it comes to fingerprints, they have to be identifiable and compared to fingerprints of known suspects.The idea behind ArroGen’s technology, though, is to let investigators glean far more information from what the perp leaves behind.
The French criminologist, Edmond Locard, once said every perpetrator of a crime brings something into the crime scene and leaves with something from it.
“We’ve increased very significantly the amount of data that can be taken from a crime scene to help support law enforcement’s hypothesis about how a crime occurred or did not occur,” Dale said.
This kind of fingerprint analysis opens up all kinds of new investigation avenues. Say there is a suspected meth lab operating out of someone’s home. Fingerprints from a child living in the home could be tested for the drug, possibly giving police the probable cause they need to search the house, Dale said. Likewise, a company could use the technology to replace drug testing that uses urine or hair, both of which only provide a snapshot into the past, or to replace a blood draw, which gives a snapshot of present drug levels but is an invasive test. The product would be useful in environments that have a zero tolerance policy toward drugs, such as parole or probation offices, correctional facilities, as well in the transportation field, as pilots, drivers, and passengers can be tested for drugs as well as explosives, Dale said.
“There’s a billion airline passengers a year who go through security. The technology could be used to screen those individuals for explosives, and pilots for any type of controlled substances or substances that could cause impairment,” Dale said.
There is a cost to a test being less invasive: It doesn’t require someone’s permission to be conducted. Civil liberties advocates fear that our rights could be violated without us even realizing it – with a test whose accuracy is not yet known.
“We generally think if you’re intruding into people’s bodies, you shouldn’t be able to do that without probable cause,” said Jay Stanley, senior policy analyst for the American Civil Liberties Union.
Stanley likened ArroGen’s testing to DNA testing done when a suspect throws away a cigarette butt or can of soda or licks an envelope. It’s possible for police to test those items and obtain DNA from them without the subject’s consent, which he and his organization oppose.
“We don’t think police should be testing people’s DNA without a warrant based on probable cause. I think it’s safe to say the same should hold for other tests into bodily secretions,” he said, referring to fingerprint residue. In other words, Stanley argues, police should have probable cause before conducting the fingerprint test—not using these tests in order to create probable cause.
“We’re always concerned if companies or government agencies are trying to look into how you’re living your life when they don’t have a need or right to know,” Stanley said.
“We are a science and technology company providing advanced solutions that serve those who fight crime and terror,” said ArroGen’s Mark Dale in response. “We serve law enforcement, public safety, and government.”
How those entities ultimately use ArroGen’s technology will be for them—and the courts—to decide.