In vitro sensitivity of commercial scanners to microchips of various frequencies.

OBJECTIVE

To evaluate sensitivity of 4 commercially available microchip scanners used to detect or read encrypted and unencrypted 125-, 128-, and 134.2-kHz microchips under controlled conditions.

DESIGN

Evaluation study.

SAMPLE POPULATION

Microchip scanners from 4 manufacturers and 6 brands of microchips (10 microchips/brand).

PROCEDURES

Each microchip was scanned 72 times with each scanner passed parallel to the long axis of the microchip and 72 times with each scanner passed perpendicular to the long axis of the microchip. For each scan, up to 3 passes were allowed for the scanner to read or detect the microchip. Microchip and scanner order were randomized. Sensitivity was calculated as the mean percentage of the 72 scans for each microchip that were successful (ie, the microchip was detected or read). Results-None of the scanners had 100% sensitivity for all microchips and both scanning orientations, and there were clear differences between scanners on the basis of operating frequency of the microchip, orientation of the microchip, and number of passes used to detect or read the microchip. For the 3 scanners designed to detect or read microchips of all 3 frequencies currently used in the United States, sensitivity was highest for 134.2-kHz microchips and lower for 125- and 128-kHz microchips. None of the scanners performed as well when only a single pass of the scanner was used to detect or read the microchips.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that use of multiple passes in different directions was important for maximizing sensitivity of microchip scanners.