Tagging of individual embryos with electronic p-Chips.

Collecting information about biochemical processes occurring inside a single cell or embryo is traditionally done either using fluorescent dyes with microscopy or via microelectrode voltage-clamp techniques. This paper demonstrates that a more direct method - transmission of information using an electronic chip implanted in an embryo - is feasible. A light-activated microtransponder with dimensions 250 μm × 250 μm × 100 μm (a "p-Chip") was implanted into a blastula-stage frog (Xenopus laevis) embryo. To implant the chip, a small slit is made in the blastocoel roof with an electrolytically-sharpened tungsten needle, and the p-Chip is inserted using fine forceps. The chip is activated when illuminated by a 60 mW focused laser beam, which causes the p-Chip to send its numeric ID to a nearby receiver. At no time during signal transmission does a wire or other type of object come in contact with or penetrate the epidermal layer covering the p-Chip. The embryo survives the procedure, extruding the chip after approximately 3 h. The method shows promise for studies including voltage potential, pH and other parameters.