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.

Piezoelectric transducer design for an ultrasonic scalpel with enhanced dexterity for minimally invasive surgical robots

“…Some researchers selected the silicon to make the waveguide of ultrasonic scalpels, considering its superior mechanical and thermal properties. 6,16 However, the procedure to fabricate silicon is complex, and the produced micro-crack can lead to the failure of waveguide. Meanwhile, stainless steel is selected to fabricate the back slab, which can reduce the acoustic energy transmitted to the transducer's back end.…”

“…Unlike high-frequency electric scalpels, ultrasonic scalpels rely on ultrasonic vibrations and ultrasonic energy to complete cutting and hemostasis of tissues. 5,6 Compared with high-frequency electric scalpels, ultrasonic scalpels significantly reduce the cutting-induced smoke and effectively keep the surgical field of view clear to avoid accidental injuries, especially when the surgical site locates close to major organs. 7 Moreover, the thermal damage to surrounding tissues caused by ultrasonic scalpels is much smaller than that caused by electric scalpels or laser scalpels.…”

“…Friedrich et al. 6,15 have designed a light and powerful planar ultrasonic micro-scalpel, which consists of a silicon horn as well as two PZT actuators bonded to each surface of the horn and driven in the transverse mode. Sadiq et al.…”

Development and Evaluation of a Titanium-Based Planar Ultrasonic Scalpel for Precision Surgery

“…Multiple studies have shown that the outcomes of ultrasonic dissection are associated with less tissue damage compared with electrosurgery [13][14][15][16]. However, their use is limited to a few fields of intervention due to the size, weight, and cost of the current systems [11,17,18]. This work aims to develop a new generation of ultrasonic microscalpel transducers for precision surgery.…”

“…Other research [18,20,21] reported the development of a miniaturized planar ultrasonic scalpel design based on micromachined silicon. In contrast to a standard Langevin transducer [19,22,23] equipped with a stack of piezoelectric discs, piezoelectric plate actuators were used, mounted on both sides of the planar silicon structure and operated in its transverse resonant mode (d 31 ).…”