Fingerprints are not just important in forensics and the identification of people; they can also be used for security clearance, access control, and the authentication of documents. In the journal Angewandte Chemie, Chinese researchers have now introduced a new fast method to make fingerprints visible at high resolution.
Fingerprints consist of sweat, oil, and compounds picked up from the environment. Latent fingerprints are often not identifiable with the naked eye; but many methods have been developed to make them visible. A team led by Bin Su at Zhejiang University (Hangzhou, China) has now added another interesting method to the mix. Their process is based on electrochemiluminescence.
Electrochemiluminescence consists of the following phenomenon: application of an electric voltage causes electrons transferred to an electrode from a chemical compound, such as a ruthenium complex, which further reacts with a partner, typically tripropylamine. The product formed is in an electronically excited state; it returns to its ground state by giving off light.
The researchers use a small glass plate coated with indium tin oxide or just a piece of stainless steel plate as the electrode. A fingerprint is transferred to this plate and then a solution containing the reactants is added. In the places where the fat-containing components of the fingerprint cover the plate, the electrode is inactive; the electrochemical reaction cannot take place, and no light is emitted. This produces a negative image of the fingerprint that can be recorded with a CCD camera.
This direct, fast, and simple method makes both fresh and old fingerprints visible without destroying them. The fingerprints are so well-resolved that it is possible to make out not only the ridge pattern, but also fine details like the branching and ends of lines, and even the tiniest features, like the distribution of pores in the grooves. These details are helpful in the identification of incomplete fingerprints. No complex procedures are needed to prepare the sample. In addition, there is no vapor or dusting involved for the user, unlike in many conventional processes.
Electrochemiluminescence can also be used in a second mode, which shows the fingerprint as a positive image. In this case, the fingerprints are first treated with a reagent that binds to components of the fingerprints. After the reaction partners are applied, only the lines emit light. This mode could be a starting point for the development of methods to detect drugs and other substances that the person who made the prints either ingested or came into contact with.
Bin Su | Angewandte Chemie
New type of photosynthesis discovered
17.06.2018 | Imperial College London
New ID pictures of conducting polymers discover a surprise ABBA fan
17.06.2018 | University of Warwick
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...
Water molecules exist in two different forms with almost identical physical properties. For the first time, researchers have succeeded in separating the two forms to show that they can exhibit different chemical reactivities. These results were reported by researchers from the University of Basel and their colleagues in Hamburg in the scientific journal Nature Communications.
From a chemical perspective, water is a molecule in which a single oxygen atom is linked to two hydrogen atoms. It is less well known that water exists in two...
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
15.06.2018 | Materials Sciences
15.06.2018 | Ecology, The Environment and Conservation
15.06.2018 | Power and Electrical Engineering