These microscopic images of the micro-injector show: (a) a zebrafish embryo held in place, (b) the needle being inserted, (c) blue dye being injected and (d) the needle coming out. (McMaster)

Engineers at McMaster University in Hamilton have built a palm-sized device that can automatically inject proteins or drugs into a series of individual cells like an assembly line.

The researchers say their device has the potential to speed up drug development and genetic engineering, and could even lead to better control over in-vitro fertilization.

"This device is to drug discovery what the assembly line was to the automobile or the silicon chip to information technology," said Ravi Selvaganapathy, assistant professor of mechanical engineering at McMaster and co-author of the research published this week in the journal Lab on a Chip.

"It turns what was a complex, resource-intensive process available to a few into an automated, predictable, reliable and low-cost system accessible to almost anyone," said Selvaganapathy.

'Printed' on silicon chip

In their research paper, graduate student Arash Noori and his colleagues describe their microfluidic micro-injector.

In tests on zebrafish embryos, the device had a success rate of nearly 80 per cent in injecting a blue dye into the cells.

The micro-injector is "printed" on a silicon chip, with a channel about as wide as the cell itself guiding it to the injection site. The cell is held in place by suction, while a needle just 10 micrometres wide (about a tenth the width of a human hair) plunges into it.

The dosage of the injection and the position of the needle tip are controlled electronically, so there's no need for a microscope to monitor the process.

The researchers said their micro-injector format could allow for needles that are just 0.1 micrometres in diameter, half the size of the smallest injectors now available.

Selvaganapathy and his colleagues said the low cost and high speed of the device could make drug development and genetic engineering much more efficient, as well as make in-vitro fertilization faster and more accurate.

"The micro-injectors can easily be run in parallel and allow for scientists to test far greater combinations of materials in a much shorter time than current processes," said Selvaganapathy.