Microelectromechanical Systems (MEMS), tiny mechanical devices built using semiconductor manufacturing techniques, are all around us. When a car airbag senses rapid deceleration and fires, it’s because of a MEMs accelerometer. When you use an inkjet printer, MEMS devices pump the ink. These miniature marvels are at work today in gyroscopes, micro-fuel cells, digital displays, optical fiber switches, fingerprint sensors and microphones; they are ubiquitious. And the Draper Laboratory, which has been on the cutting edge of MEMS development since the early 1980s, is developing new application areas for this exciting field of technology.
MEMS-Based Drug Delivery and Microfluidic MEMS
In the future, tiny implantable devices could deliver drugs to the cochlea, part of the inner ear, and allow for the treatment of hearing loss and other auditory and vestibular diseases. Microfluidic systems, consisting of a drug reservoir, valve, pump and flow sensor, are currently being developed by Draper researchers to improve inner ear drug delivery and the hope is that they will be readied for human clinical trials.
A collaboration with Children’s Hospital Boston (CHB) comes in a similarly small size, but the implications could be huge for the sufferers of septic shock – who number 750,000 annually in the US, with a mortality rate between 30 and 50 percent. Draper and CHB are developing a miniature filtration device to pump blood out of the body, clear it of infectious agents - like fungal cells - and deliver it back to the body, effectively removing the pathogens that trigger septic shock. “Fungal infections are especially problematic and they do infect infants and newborns and premature babies, one of the classes of patients that will often die if they get to this point,” says Draper’s Jason Fiering, who is working on this project headed by Donald Ingber, MD, PhD, of Children’s Hospital Boston. “This is a whole body system where we’d remove the blood, clean it , and return it to the patient.”
MEMS-based drug delivery and Microfluidic MEMS technology represent a leap forward that few could have envisioned two decades ago. While a significant amount of MEMS work now focuses on improving human health, MEMS research and development at Draper had a different origin. The lab began by expanding core technologies in guidance, navigation and control into MEMS, yielding high-performance MEMS gyros and accelerometers.
The Draper Laboratory first began building a presence in this burgeoning field in 1984. A Draper engineer, Burton Boxenhorn, envisioned a very tiny gyroscope that could be built through silicon micromachining; he turned to Draper’s Paul Greiff for this task. Three years later, in 1987, the duo had a notable achievement, becoming the first ever to detect rate with a silicon MEMS gyro.
In 1991, the laboratory formed a working group which focused on its MEMS devices – still primarily gyros and accelerometers. But change was on the horizon. “Around 1992, we had a briefing here where we showed these ideas to an independent panel with people from MIT and other (institutions). Out of that discussion came the tuning fork gyro, the one we make now and have been perfecting since,” said Draper’s Neil Barbour. “After that, it just grew – the MEMS group got larger. We had new ideas to make more than just gyros and accelerometers.”
In 1993, Draper engineers produced the first micromachined silicon tuning-fork gyroscope. The tuning fork gyro proved to be the foundation for future MEMS work at Draper.
An Industrial Partner And Achievements In Defense
As the Draper Laboratory considered the hefty costs of developing this technology and the potential for commercialization, it made sense to bring on an industrial partner. So in 1993 the lab entered an alliance with Rockwell International, with the intention of bringing inertial MEMS sensors into a variety of consumer applications, from antilock brakes to camcorders (image stabilization). “There were a couple of niceties to it. Rockwell was really focused on automotive applications and that left a lot of the military applications to us,” said Draper’s Tony Kourepenis. “We didn’t marry someone like us. There was some good synergy in terms of what they wanted to do and what we wanted to do.”
Rockwell funded the laboratory’s effort to develop low cost MEMS and that meant getting electronics implemented in application-specific integrated circuit (ASIC) form – this further benefited Draper. “This really gave us the path to miniaturization. Apart from giving them the low cost technologies they needed to address the automotive marketplace, it really enabled us to shrink this technology down,” added Kourepenis.
Around this time, Draper also began to establish its position as a leader in MEMS development for the Department of Defense. The laboratory saw the potential for applying MEMS in guided projectiles and the Extended-Range Guided Munition (ERGM) demonstration program became a major success story. “What we designed was a coffee can sized set of avionics. It had a GPS, the mission processor and power regulations and subsystem inside. It basically took an old projectile, sliced it in half, and inserted this avionics package,” said Kourepenis. “It demonstrated a lot of firsts: the first MEMs system that was able to survive and operate post-launch, the first reacquisition of P(Y) code … all of the work to prove that you could guide a munition to a target was done on that program.”
Draper continued to advance MEMS technology for DoD. In 1998, the laboratory developed enabling technologies for low cost miniature guidance systems under the Competent Munitions Advanced Technology Demonstration (CMATD) program. A miniature INS/GPS guidance system, occupying eight cubic inches, was developed using a Draper Micro-Mechanical Inertial Sensor Assembly (MMISA).
In 2000, the Defense Advanced Research Projects Agency (DARPA) and the Air Force Research Lab (AFRL) sponsored Draper to develop and demonstrate the MEMS IMU (DARPA MMIMU). The first MMIMU system was built and tested in August 2002, representing the highest performance attained on an all-silicon IMU. The success of these projects was largely due to the diverse talents of Draper’s staff. “We had a lot of really talented engineers who were multidisciplinary. We had very good people in sensor design, mechanical design. We had very good people in electronics design, ASICS development. The packaging folks were superb and we had good systems engineering,” said Kourepenis. “We had very well defined objectives and a lot of motivation to meet those objectives. When you bring talent and a well defined problem together, generally you’ll be very successful and we really were.”
A Diverse Slate Of Projects
MEMS projects run the full gamut at Draper – and that allows for tremendous growth. The lab has gone from a handful of staffers working on MEMS projects in the 1980s to over 30 working on MEMs technologies for environmental monitoring, chem-bio sensing, wireless communications, and numerous projects within the realm of BioMEMS (drug delivery, tissue engineering, microfluidics). “Now we can interact with cells, we can interact with biological systems, we can measure biological systems, and we can create engineered biological systems all on a relevant size scale,” says Amy Duwel, group leader for Draper’s Microelectromechanical Systems Division. “That’s just a large fundamental argument for why MEMS has a future in bio.”
Tissue engineering with MEMS could play a role in organ replacement and wound healing. Jeff Borenstein, director of the biomedical engineering center at Draper, is among those working in this area. He and his team are creating tiny scaffolds made of biodegradable or bio-absorbable polymers with channels in which vascular cells can attach and multiply. Once a blood vessel network is viable, the goal is to spur the growth of tissues and organs around it.
Space has been another huge area for Draper MEMS work. In early 2007, the lab demonstrated the effectiveness of the Inertial Stellar Compass (ISC), representing the first use of a MEMS gyro in a spacecraft attitude determination system. The ISC uses one half the power and mass of conventional systems. As always, shrinking the size of systems is a huge plus. “People still need smaller devices and high performance, so pushing MEMS as far as we can go to deliver that is something we’re motivated to do,” says Duwel. “We believe the applications will be there.”
- Jeff Meredith
- I am a researcher, reporter and conference producer with experience spanning the aerospace & defense, biopharma, chemical, consumer electronics, energy, homeland security, human resources and IT markets.
In January I rejoined Worldwide Business Research, where I serve as program manager for Consumer Returns, SCMchem and the Digital Travel Summit.
I have an M.S. in science and medical journalism from Boston University (Dec 2008) and did my undergraduate work at Indiana University, majoring in journalism and political science (May 2001). After interning for the Chicago Tribune as a collegian, I landed my first real gig in the Windy City: I was a senior technology writer for I-Street magazine (Sept 2001-Feb 2003). I covered nanotech and biotech startups. From March-November 2003, I worked for a newsletter publisher (Exchange Monitor Publications) in DC, covering congressional hearings, the NRC & DHS.