Non-Thermal Plasma: A Promising Tool for DNA Decontamination in Forensic VMD Chambers
Organized by: International Forensic Scientist Awards
Website: forensicscientist.org
14th Edition of Forensic Scientist Awards 26-27 September 2025 | Mumbai, India
In forensic science, both fingerprints and DNA evidence play crucial roles in solving crimes. However, one persistent challenge is cross-contamination — when traces of DNA are accidentally transferred between items of evidence during analysis. Preventing this is especially important when using Vacuum Metal Deposition (VMD), a powerful technique for developing fingerprints on a wide range of surfaces.
Traditionally, decontamination methods like UV-C light or chemical solvents have been used. But UV-C has its limitations: it can only reach areas directly exposed to light, while solvents may interfere with delicate vacuum-based equipment. This is where non-thermal plasma (NTP) enters the picture.
What is Non-Thermal Plasma (NTP)?
Non-thermal plasma is an ionized gas capable of breaking down biological material, including DNA. Unlike UV-C, plasma can penetrate tiny crevices and irregular surfaces, offering an edge in decontamination where traditional methods fall short.
The Proof-of-Concept Study
Researchers tested different plasma conditions inside a forensic VMD chamber using human cells and cell-free DNA samples. Variables included:
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Power settings: medium vs. maximum
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Exposure times: 30 minutes, 1 hour, and 2 hours
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Pressure levels: 1.68, 2, and 4.27 × 10⁻¹ mbar
Key findings:
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Plasma treatment reduced DNA concentrations by around 100-fold.
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The most effective condition was 1 hour at maximum power and 2 × 10⁻¹ mbar pressure.
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UV-C light still performed better for direct exposure, but NTP was superior at eliminating DNA in areas hidden from line of sight.
Why Does This Matter?
This study highlights NTP as a safe, solvent-free, and highly effective option for decontaminating forensic instruments like VMD chambers. By reducing DNA contamination risks, forensic scientists can more reliably sequence fingerprint and DNA analysis without compromising evidence integrity.
Looking Ahead
Future research will focus on fine-tuning plasma conditions — power, pressure, and exposure to ensure complete DNA elimination. If optimized, NTP could become a standard decontamination method in forensic workflows, improving both accuracy and trust in forensic evidence.
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