Handheld Raman is an excellent tool for police, border control and first responders to identify unknown threats quickly in the field. Narcotics, explosives and other dangerous chemicals can pose serious threats to the operators and being able to quickly identify them reduces the risk for and improves the efficiency of the operators. With the new Serstech SERS kit, the detection levels are brought to a new level.
The principle behind Raman instruments is based on physical properties of certain molecules and the electromagnetic signals they emit when energy is added to them by the instrument lasers. The signal is very weak, which requires the instruments to be highly sensitive, something that has only become possible to do in a handheld instrument in the last decade. Some substances are in addition not very Raman active, which means that the signal is even weaker, often weak enough to make it virtually impossible to detect. This is where SERS technology comes in. Serstech’s SERS kit greatly amplifies the signal to make it easily detectable with a handheld Raman instrument.
SERS stands for Surface Enhanced Raman Spectroscopy and is also the first part of the company name Serstech. Serstech was founded in 2006 and the idea from the beginning was to develop small Raman instruments and SERS technology to make the instruments highly sensitive, well beyond what was commercially available at the time. Serstech’s SERS kit was launched in 2019 and is now in use by narcotics police and others who need to identify low or very low concentrations of illegal substances, which is sometimes the case in street-quality narcotics seized by police.
SERS works by creating a resonance between the dissolved sample and a silicon wafer that has been nano-coated with silver particles. Due to the resonance, the signal the instrument can read is amplified by a factor of at least 10,000 and signals from low concentration samples and from substances that have low Raman activity can be read and identified.
Colored substances, such as typical ecstasy pills and many organic compounds, are hard to identify for any Raman instrument. The reason for this is that electrons are excited by the laser emitted by the instrument and the excitation energy is emitted when the electron goes back to its original state. This very strong energy can blind the instrument and also obfuscate the Raman signal of the substance. By using the SERS kit, with the resulting amplification of the Raman signal, even many fluorescent samples can be identified by handheld Raman instruments.
Serstech’s SERS kit is patented and consists of an instrument accessory that is connected at the tip of the instrument and disposable SERS surfaces that are inserted in the kit. To identify a solid sample using the SERS kit, the solid sample needs to be dissolved in methanol and the solution is applied to a SERS surface. After a few seconds, the solvent has evaporated and the surface is inserted into the kit and the instrument identifies the substance. The identification of the substance is typically made in 10-20 seconds and the instrument is operated in the same way as if the SERS kit was not attached.
The SERS kit works with all of Serstech’s instruments – the Serstech 100 Indicator, the Serstech Arx and Serstech Arx+.