title: Silicon micromachined ultrasonic scalpel for the dissection and coagulation of tissue.
abstract: This work presents a planar, longitudinal mode ultrasonic scalpel microfabricated from monocrystalline silicon wafers. Silicon was selected as the material for the ultrasonic horn due to its high speed of sound and thermal conductivity as well as its low density compared to commonly used titanium based alloys. Combined with a relatively high Young's modulus, a lighter, more efficient design for the ultrasonic scalpel can be implemented which, due to silicon batch manufacturing, can be fabricated at a lower cost. Transverse displacement of the piezoelectric actuators is coupled into the planar silicon structure and amplified by its horn-like geometry. Using finite element modeling and experimental displacement and velocity data as well as cutting tests, key design parameters have been identified that directly influence the power efficiency and robustness of the device as well as its ease of controllability when driven in resonance. Designs in which the full- and half-wave transverse modes of the transducer are matched or not matched to the natural frequencies of the piezoelectric actuators have been evaluated. The performance of the Si micromachined scalpels has been found to be comparable to existing commercial titanium based ultrasonic scalpels used in surgical operations for efficient dissection of tissue as well as coaptation and coagulation of tissue for hemostasis. Tip displacements (peak-to-peak) of the scalpels in the range of 10-50 μm with velocities ranging from 4 to 11 m/s have been achieved. The frequency of operation is in the range of 50-100 kHz depending on the transverse operating mode and the length of the scalpel. The cutting ability of the micromachined scalpels has been successfully demonstrated on chicken tissue.
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Microengineering (IMT), Sensors, Actuators and Microsystems Laboratory (SAMLAB), Neuchâtel, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Lockhart
authors.forename: F
authors.initials: F
authors.lastname: Friedrich
authors.forename: D
authors.initials: D
authors.lastname: Briand
authors.forename: P
authors.initials: P
authors.lastname: Margairaz
authors.forename: J-P
authors.initials: JP
authors.lastname: Sandoz
authors.forename: J
authors.initials: J
authors.lastname: Brossard
authors.forename: H
authors.initials: H
authors.lastname: Keppner
authors.forename: W
authors.initials: W
authors.lastname: Olson
authors.forename: T
authors.initials: T
authors.lastname: Dietz
authors.forename: Y
authors.initials: Y
authors.lastname: Tardy
authors.forename: H
authors.initials: H
authors.lastname: Meyer
authors.forename: P
authors.initials: P
authors.lastname: Stadelmann
authors.forename: C
authors.initials: C
authors.lastname: Robert
authors.forename: A
authors.initials: A
authors.lastname: Boegli
authors.forename: P-A
authors.initials: PA
authors.lastname: Farine
authors.forename: N F
authors.initials: NF
authors.lastname: de Rooij
authors.forename: J
authors.initials: J
authors.lastname: Burger
mesh_terms: D000818:Animals; D002645:Chickens; D004210:Dissection / Q000295:instrumentation*; D017097:Electric Impedance; D004867:Equipment Design; D020342:Finite Element Analysis; D006487:Hemostasis; D008422:Materials Testing; D015203:Reproducibility of Results; D012825:Silicon / Q000737:chemistry*; D013525:Surgical Instruments; D013552:Swine; D014159:Transducers; D014465:Ultrasonics / Q000295:instrumentation*
chemical_list: D012825:Silicon