Tiny Pump, Big Promise
Posted date : May 27, 2009

Debiotech has developed a new generation of disposable drug delivery pumps based on SOI-MEMS. Diabetes patients will be the first beneficiaries.

The first application of the tiny SOI-MEMS Nanopump™ will be for treating diabetes. (Courtesy: Debiotech)

An SOI-based MEMS solution developed by Debiotech and manufactured by STMicroelectronics is poised to make a major impact on the lives of people suffering from diabetes and other long-term illnesses.

At the heart of the system is the Nanopump™, a volumetric membrane pump. The pump consists of a membrane micromachined in an SOI wafer, which is in turn sandwiched between two Pyrex™ plates with throughholes. A piezoelectric actuator moves the membrane to compress and decompress the fluid in the pumping chamber.

1st app: insulin

The first application of the Nanopump is the Insulin Nanopump™ for people with diabetes.

The world’s 12 million type-1 or insulin-dependent diabetics have to check their blood repeatedly throughout the day, then self-inject appropriate levels of insulin to adjust for variations in glucose levels caused by meals.

While most diabetics use syringes, a growing number are turning to electronic “insulin pumps” offered by leading medical technology companies. The current generation of pumps is improving, but there are still drawbacks, notably upfront cost and bulkiness.

A typical, classic pumping system consists of a cannula that stays in place in the skin for several days, and an electronic insulin-pumping unit, that is attached to the cannula via a catheter of about 18” (45cm). The attached pumping unit – typically about the size of a pack of playing cards – must be belted in place or carried in a pocket or pouch day and night.

By replacing the heart of the pumping system with a microfluidic MEMS chip, Debiotech has reduced the Insulin Nanopump to about a quarter the size of existing systems. Because it’s so small, the unit can be attached directly to the skin patch, eliminating the nuisance (and potential danger) of the loops of catheter. For the user, it’s also far more visually discrete – a much appreciated advantage.

SOI for precision, size, savings

Beyond the aesthetics and convenience, the use of SOI wafers for fabricating the Nanopump MEMS device has significant medical and economic advantages.

The SOI-based structure allows for the highest reliability in the smallest possible package, enabling very tight control and precision of the pumping mechanism. The flow rate is steady, and it is insensitive to pressure, temperature, viscosity and aging.

It also offers extreme dosing precision. Each pump actuation delivers just 200 nanoliters of insulin – approaching nearly continuous delivery.

From a manufacturing standpoint, the Nanopump is designed to be part of the disposable supply pack, so cost is critical. SOI enabled a drastic reduction in die size, making if far cheaper to produce than a bulk silicon equivalent. In turn, the tiny chip enables a far smaller – and less expensive – pumping unit.

STM’s SOI MEMS expertise

For volume manufacturing, Debiotech turned to STMicroelectronics for its expertise in large-scale production of microfluidic MEMS devices. As Dr. Frédéric Neftel, President and CEO of Debiotech noted, “The collaboration with ST has proven to be extremely efficient in terms of time and achievements.”

Because Debiotech is strictly an R&D company, the Insulin Nanopump will be licensed exclusively to a major medical technology company.

The Nanopump itself, however, could be used and is available for licence in other drug delivery devices requiring high precision over a wide range of conditions.

As such, it heralds a new era in continuous drug delivery, combining the highest level of reliability and performance with previously unmet levels of convenience and safety for the patient.

“Working with our key partner Debiotech, we are readying a tiny piece of silicon that can make a huge difference to millions of diabetes patients around the world.”

Benedetto Vigna,
Group Vice President and General Manager,
STMicroelectronics MEMS and Healthcare, RF and Sensors Division.

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