title: Latent fingerprint visualization using a scanning Kelvin probe in conjunction with vacuum metal deposition.
abstract: The application of vacuum metal deposition before scanning Kelvin probe visualization of fingerprints is investigated. The potential contrast between fingerprint ridges and furrows is maximized by the use of silver deposition for non-noble metals and gold-zinc deposition for noble metals. The higher susceptibility of eccrine fingerprints to vacuum metal overdeposition is confirmed. Additionally, fingerprints are best developed individually and by building the metal deposition slowly to protect against overdevelopment and variation in the rate of metal condensation. The progress of the metal deposition can be monitored using the scanning Kelvin probe by reference to the change in potential and continuity of the new potential on the surface. The use of acetic acid solution for the recovery of overVMD-developed samples is shown not to be useful. Applying the metal deposition has the additional prospect of increasing surface conductivity and homogeneity and both can aid fingerprint visualization using the scanning Kelvin probe.
authors.affiliation: Materials Research Centre, College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP, U.K.
authors.forename: Hefin
authors.initials: H
authors.lastname: Dafydd
authors.forename: Geraint
authors.initials: G
authors.lastname: Williams
authors.forename: Stephen
authors.initials: S
authors.lastname: Bleay
mesh_terms: D019342:Acetic Acid; D000497:Alloys; D000535:Aluminum; D003300:Copper; D003878:Dermatoglyphics; D055664:Electrochemical Techniques; D006046:Gold; D006801:Humans; D007202:Indicators and Reagents; D020527:Microscopy, Scanning Probe / Q000379:methods*; D012834:Silver; D013193:Stainless Steel; D013499:Surface Properties; D014618:Vacuum; D014835:Volatilization; D015032:Zinc
chemical_list: D000497:Alloys; D007202:Indicators and Reagents; D013193:Stainless Steel; C048399:brass; D012834:Silver; D006046:Gold; D003300:Copper; D000535:Aluminum; D015032:Zinc; D019342:Acetic Acid
keywords: contrast development; fingerprint; forensic science; metal surface; scanning Kelvin probe; vacuum metal deposition