Micro-surgical Tools and Morphing Aircraft Wings
Dr. Mary Frecker
Associate Professor of Mechanical and Nuclear Engineering
Surgical tools for cutting and suturing inside the body allow surgeons to work via small incisions hastening healing, leaving smaller scars, and lowering the length of costly hospital stays. Called minimally invasive surgery, these techniques are used frequently for sports injuries (arthroscopy) and abdominal surgery (laparoscopy). Working with colleagues at Penn State’s Hershey School of Medicine, and in the Particulate Materials Center in the Penn State Materials Research Institute, Mary Frecker is designing a new generation of micro surgical instruments to help overcome the limitations in today’s design and manufacture of minimally invasive surgical tools.
"We have reached the limits of what can be done with today’s materials and today’s manufacturing techniques," Dr. Frecker asserts. "There is a need for multifunctional instruments that are an order of magnitude smaller than current instruments. We’re talking about a tiny scissors-forceps that can be used, for example, in surgery on the retina. With an instrument that size you can do sutureless surgery, self-healing incisions."
Collaborating with Randy Haluck, MD, Director of the Minimally Invasive Surgery Program at Penn State’s Hershey Medical School, Dr. Frecker first worked on multifunctional laparoscopic instruments of the same size as current models, roughly 5 to 10mm in diameter at the tip. Their idea, based on extensive video studies of actual surgeries, was to reduce the necessity of removing the tool from the site to exchange instruments for tasks such as cutting and suturing. If they could design a tool that could both cut and grasp, there would be less risk of damage to tissue during exchanges and a real savings in operating room costs.
"In minimally invasive surgery they use a host of instruments which are continually inserted and removed. During each instrument exchange there is a risk of inadvertent tissue damage. If the patient starts to bleed internally, they may have to be opened up anyway. Another important issue is that exchanges may disrupt the surgeon’s concentration," says Dr. Frecker.
The next challenge was to make multifunctional instruments at an order of magnitude smaller, in the .5 mm diameter range. This is a size that may be useful for flexible endoscopy. The idea is to use a flexible scope equipped with a light source, camera, and working channels for instruments to be inserted and removed. The scope could be introduced through the throat and into the abdomen through a small hole in the stomach.
Multipurpose surgical tool for cutting and grasping
"The whole idea of exchanging instruments becomes very important with flexible endoscopy," Frecker says, "because you don’t want to have to snake the whole instrument in and out of the abdomen every time you need to change the tool tip."
The problem she faced with making multifunctional instruments on that size scale was with the hinges and pin joints that were necessary to making typical cutting and suturing tools. This posed a nearly impossible problem in assembly. Her solution was a single-piece compliant design, two arms coming together in a V that could be clamped together for holding or twisted for cutting.
"Anything more complex and 3-D, we just can’t do it with the conventional material and manufacturing techniques," she says. "This is where Jim Adair comes in with his nanoparticulate materials."
The Lost Wax Method
James Adair, Professor of Materials Science and Engineering and Director of the NSF Particulate Materials Center, uses Mary Frecker’s designs to fabricate sub 100 micron surgical tools using an ancient casting technique called the lost wax method. Pure zirconium nano particles are gel cast into a mold and sintered on a chip. "This is the lost wax method invented by the Phoenicians 5 or 6,000 years ago, but using nanomaterials for miniaturization," Adair says. After the instruments are hardened, they are sealed and coated with gold palladium using sputter coating techniques.
Each arm of this nanoparticulate surgical tool
is no thicker than the finest human hair.
"The nice thing about these nanoparticles is that with extremely small particles we can get small feature sizes and sharp edges on our parts. There is also a strength benefit compared to ordinary materials. Jim can make these micro-sized parts that are biocompatible, are able to be sterilized, and can withstand the stresses of the mechanical loads they will be exposed to," Frecker says. Incision Tech is in the process of licensing Dr. Frecker’s patent and has supported their research, as has the Whitaker Foundation and the Life Sciences Greenhouse of Central Pennsylvania.
Electroactive Polymers
In another bio-related project wrapping up this year, Dr. Frecker is working with Alan Snyder at Hershey, Prof. Qiming Zhang, and Eric Mockensturm, assistant professor of mechanical engineering, on modeling active diaphragms for future mechanical heart assist pumps. These devices are placed inside the body to assist a patient’s heart, usually while they are awaiting a heart transplant. "Electroactive polymer acts in a way very similar to muscle, where there is a mechanical strain in response to an electrical stimulus. We’ve been looking at dielectric elasomers that have very large strain responses as active replacements for the current passive diaphragms in the assist pump," she says. This work is sponsored by the National Institutes of Health.
Morphing Wings
7q The military is interested in aircraft that can do what birds do, which is change the shape of their wings during flight," Dr. Frecker says about the work she is doing with collaborator George Lesieutre, Head of the Department of Aerospace Engineering. "When hawks loiter, or circle around, their wings are spread out far. Then when they see a small mouse on the ground, they sweep their wings back and pull them in for the high-speed maneuver to dive down and snatch up the mouse."
Dr. Mary Frecker with EDOG grad student Shamus Cronin
The question for the engineers is how to design an underlying structural mechanism in the airplane wings that will give them a large shape change but also withstand the air loads. "Birds use distributed actuation, with muscles distributed along their wings," she says. "For aircraft we would like to have a morphing wing with a smaller number of actuators, due to weight considerations. We are working on a system of cables and struts that can provide large changes in sweep and span using a relatively small number of actuators." Their work on morphing aircraft wings is supported by the Air Force Office of Scientific Research.
In a similar project with Farhan Gandhi, associate professor of aerospace engineering, Dr. Frecker is working on morphing the rotor blades of helicopters. The issue they are addressing with helicopter rotors is vibration and noise. If they can change the shape of the rotor blade during flight, "adjust the camber of the airfoil," then they can reduce vibration and noise. Their work on morphing rotor blades is supported by the National Rotorcraft Technology Center through the Penn State Rotorcraft center.
Dr. Frecker and Dr. Tim Simpson, along with a dozen graduate students and several undergraduates, make up the Engineering Design and Optimization Group. Meeting in an 1100-plus-square-foot research facility on the third floor of the new Leonhard building, the EDOG members perform theoretical, computational, and experimental research that will impact both our health and national defense.
Education
Ph.D., ME, University of Michigan, 1997
M.S., ME, University of Michigan, 1994
B.S., ME, University of Dayton, 1991
Contacts:
Mary Frecker, Validate to view address
Randy Haluck, Validate to view address
James Adair, Validate to view address
Alan Snyder, Validate to view address
Penn State Rotocraft Center
Selected Publications
Canfield, S., and M. Frecker. 2000. Topology Optimization of Compliant Mechanical Amplifiers for Piezoelectric Actuators. Structural Optimization, 20 (4), pp. 269-279.
Frecker, M., and S. Canfield. , 2000. Optimal Design and Experimental Validation of Compliant Mechanical Amplifiers for Piezoceramic Stack Actuators. Journal of Intelligent Material Systems and Structures, Vol. 11 , No. (5), pp. 360-369.
Edinger, B., M. Frecker, M., and J. Gardner. 2000. Dynamic Modeling of an Innovative Piezoelectric Inchworm Actuator for Minimally Invasive Surgery. Journal of Intelligent Material Systems and Structures, Vol. 11 , No. (10), pp. 765-770.
Mehta, N., R. Haluck, R., M. Frecker, M., and A. Snyder., 2002. Sequence and Task Analysis of Instrument Use in Common Laparoscopic Procedures. Surgical Endoscopy Ultrasound and Interventional Techniques, 16, pp. :280-285.
Cappelleri, D., M. Frecker, M., T. Simpson, T., and A. Snyder. 2002. Design of a PZT Bimorph Actuator Using a Metamodel-Based Approach. ASME Journal of Mechanical Design, 124:2, pp. (354-357).
Frecker, M., R. Dziedzic, R., and R. Haluck, 2002. Design of Multifunctional Compliant Mechanisms for Minimally Invasive Surgery. Minimally Invasive Therapy and Allied Technologies, 11 (5/6), pp. 311-319.
Frecker, M. , 2003. Recent Advances in Optimization of Smart Structures and Actuators. Journal of Intelligent Material Systems and Structures, 14(5), pp. 207-216.
Frecker, M., and W. Aguilera, 2004. Analytical Modeling of a Segmented Unimorph Actuator Using Electrostrictive P (VDF-TrFE) Copolymer. Smart Materials and Structures 13, pp. 82-91.
Maddisetty, H., and M. Frecker. , 2004. Dynamic Topology Optimization of Compliant Mechanisms and Piezoceramic Actuators. ASME Journal of Mechanical Design. 126(6), pp. 975-983.
Frecker, M., Schadler, J., Haluck, R., Culkar, K., and R. Dziedzic, 2005. Laparoscopic Multifunctional Instruments: Design and Testing of Initial Prototypes. Journal of the Society of Laparoendoscopic Surgeons. 9(1), pp. 105-112.
Anusonti-Inthra, P., Searjant, R., Frecker, M., and F. Gandhi,. 2005. Design of a Conformable Rotor Airfoil Using Distributed Piezoelectric Actuators. AIAA Journal . 43(8), August, 2005, pp. 1684-1695.
Abdalla, M., Frecker, M., Gurdal, Z., Johnson, T., and D. Lindner, 2005. Design of a Piezoelectric Stack Actuator and Compliant Mechanism Combination for Maximum Energy Efficiency. Smart Materials and Structures, 14 (2005), pp. 1421-1430.
Frecker, M., Powell, K., and R. Haluck, 2005. Design of a Multifunctional Compliant Instrument for Minimally Invasive Surgery. ASME Journal of Biomechanical Engineering, 127, November, 2005, pp. 990-993.
Goulbourne, N., Mockensturm, E., and M. Frecker, 2005. A Nonlinear Mathematical Model for Dielectric Elastomer Membranes. ASME Journal of Applied Mechanics, 72, pp. 899-906.
Ramrakhyani, D., Lesieutre, G., Bharti, S., and M. Frecker, 2005. Aircraft Structural Morphing using Tendon Actuated Compliant Cellular Trusses. Journal of Aircraft, 42(6), pp. 1615-1621.
