Bacterial Survivability and Transferability on Biometric Devices

The purpose of this study was to investigate bacterial recovery and transfer from three biometric sensors and the survivability of bacteria on the devices. The modalities tested were fingerprint, hand geometry and hand vein recognition, all of which require sensor contact with the hand or fingers to collect the biometric. Each sensor was tested separately with two species of bacteria, Staphylococcus aureus and Escherichia coli. Survivability was investigated by sterilizing the sensor surface, applying a known volume of diluted bacterial culture to the sensor and allowing it to dry. Bacteria were recovered at 5, 20, 40 and 60 minutes after drying by touching the contaminated device with a sterile finger cot. The finger cot was re-suspended in 5 mL of saline solution, and plated dilutions to obtain live cells counts from the bacterial recovery. The transferability of bacteria from each device surface was investigated by touching the contaminated device and then touching a plate to transfer the bacteria to growth medium to obtain live cell counts. The time lapse between consecutive touches was one minute, with the number of touches was n = 50. Again, S. aureus and E. coli were used separately as detection organisms. This paper will describe the results of the study in terms of survival curves and transfer curves of each bacterial strain for each device.