Ultrasonic Needles for Bone Biopsy

Acoustic black hole ultrasonic scalpel

Ultrasonic scalpels (USs), as the preferred energy instruments, are facing a growing need to exhibit enhanced performance with the diversification of modern surgical challenges. Hence, we proposed an acoustic black hole ultrasonic scalpel (ABHUS) in longitudinal-bending coupled vibration for efficient surgical cutting. By incorporating an acoustic black hole profile, the local bending wave velocity is reduced and the amplitude is amplified cumulatively, thus creating a high-energy region near the blade tip to enhance the cutting performance of the ABHUS. The precise physical analysis model is established for systematic design of the ABHUS and quick estimation of its frequency characteristics. The vibration simulation and experiments demonstrate that compared with the conventional ultrasonic scalpel (CUS), the output amplitude of the ABHUS significantly increases, particularly a 425% increase in bending vibration displacement. The in-vitro cutting experiment confirms that ABHUS exhibits superior cutting performance. Our design presents vast possibilities and potential for the development of high-performance ultrasonic surgical instruments, serving as an innovative supplement with extraordinary significance for application of acoustic black holes.

Needle bevel geometry influences the flexural deflection magnitude in ultrasound-enhanced fine-needle biopsy

It has been recently demonstrated that use of ultrasound increases the tissue yield in ultrasound-enhanced fine-needle aspiration biopsy (USeFNAB) as compared to conventional fine-needle aspiration biopsy (FNAB). To date, the association between bevel geometry and needle tip action has not been widely explored. In this study, we studied the needle resonance characteristics and deflection magnitude of various needle bevel geometries with varying bevel lengths. With a conventional lancet, having a 3.9 mm long bevel, the tip deflection-to-power ratio (DPR) in air and water was 220 and 105 µm/W, respectively. This was higher in comparison to an axi-symmetric tip, having a bevel length of 4 mm, which achieved a DPR of 180 and 80 µm/W in air and water, respectively. This study emphasised the importance of relationship between flexural stiffness of bevel geometry in the context of various insertion media and, thus, could provide understanding on approaches to control post-puncture cutting action by modifying the needle bevel geometry, essential for the USeFNAB application.

Stress superposition effect in ultrasonic drawing of titanium wires: An experimental study

Benefits of ultrasonic vibration have been identified in metal forming and other manufacturing processes, yet the underlying mechanism has not yet been fully understood. In this paper, influences of ultrasonic vibration on the titanium wire drawing process were investigated in terms of ultrasonic amplitude, drawing speed, and position of the die. Longitudinal vibrations were superimposed upon the die via a tailor-made ultrasonic vibrator, whose dynamic performances were predicted by finite element analysis (FEA) and examined utilizing specific instruments. A single-pass ultrasonic wire drawing platform was established to measure the forming forces under various drawing conditions, which were subsequently compared with numerical simulation results. Surface morphologies of the drawn wires were inspected by scanning electron microscope (SEM). Results show that both increased ultrasonic amplitude and lowered drawing speed contribute to decreasing the drawing forces, but the efficiency is furthered influenced by location of the die. At the half-wavelength position, a significant drawing force reduction of 66.8% (from 22.5 N to 7.45 N) was observed with the ultrasonic amplitude and drawing speed of 9μm and 100 mm/s, respectively. At the quarter-wavelength position, however, the corresponding percentage reduction is only 21%. The phenomenon could be explained by the elastic stretching oscillation of the wire based on the stress superposition hypothesis.

A longitudinal-torsional mode ultrasonic needle for deep penetration into bone

This work presents a longitudinal-torsional (L-T) composite mode ultrasonic needle device for deep bone penetration. The L-T needle is a geometrically modified version of an L-mode needle whose efficacy as a prototype ultrasonic bone biopsy device has been previously demonstrated by the authors. Finite element analysis (FEA) aided in the design of the L-T needle, with the aim of maximising the achievable torsional displacement while matching the longitudinal displacement achieved by the L-mode needle. Experimental modal analysis (EMA) of the fabricated ultrasonic device was used to identify the modal parameters and validate the FEA model. Harmonic analysis then provided an insight into how the inherent nonlinearities of the high-power transducer are affected by incorporating the geometrical features that degenerate the L mode into an L-T mode. High power characterisation shows that the longitudinal displacement amplitude of the L-T mode needle is larger than that of the L-mode needle. Comparative penetration tests in fresh Wistar rat skull were evaluated by investigating cell death and cell survival. The region of statistically significant cell death was small for both devices, with the combined axial and shear motion of the L-T device causing increased osteocyte necrosis within this region. Nevertheless, the results suggest a promising environment for post-operative healing. It is shown how this technology offers a potential technique for a surgical approach to the petrous apex, an application that requires a deep penetration into bone.

Fast and Precise Control for the Vibration Amplitude of an Ultrasonic Transducer Based on Fuzzy PID Control

This work presents a novel constant frequency ultrasonicamplitude control (CFUAC) method based on fuzzy proportional-integral-derivative (FPID) and amplitude direct feedback. The frequency shift and amplitude nonlinearity of the piezoelectric transducer (PT) are measured to determine the optimal constant control frequency of 19.2 kHz. The FPID controller is designed to adapt to the nonlinear changes in different target amplitudes and loads. A direct PT amplitude feedback method is used to improve the signal's anti-interference ability and accuracy. The 5% settling time and steady-state error of FPID can reach 92.22 ms and [Formula: see text] at the step response under 24 [Formula: see text]. The 5% settling time and steady-state error of FPID are less than 131.44 ms and [Formula: see text] at 10 [Formula: see text] under 150 N. The results confirmthat fast and precise control of the vibration amplitude of an ultrasonic transducer can be realized by the proposed method. The new CFUAC method lays a foundation for revealing the ultrasonic welding and metal processing (UWMP) mechanism and helps to expand the application of ultrasonic vibration in the fields of precision machining and high dynamic ultrasonicmedical equipment.

Optimal Design and Experimental Verification of Ultrasonic Cutting Horn for Ceramic Composite Material

We developed and optimized a block-type ultrasonic horn that can be used for cutting hard materials. The proposed block-type sonotrode consists of an aluminum horn and a tungsten carbide blade to increase the cutting of hard materials. We designed an initial ultrasonic block horn that has double slots and an exponential stepped profile. We developed a finite element model of the initial model and analyzed the characteristics of natural frequency and displacement. We formulated a DOE table and response surface to perform sensitivity analysis and analyze the correlation between the design variables and characteristics of the proposed block horn. The optimal ultrasonic block horn was derived via a multi-objective optimal design problem to maximize the amplitude uniformity of the proposed horn and frequency separation. We fabricated the optimal block horn and verified it experimentally. An ultrasonic cutting experiment was conducted to find the ultrasonic cutting force with hard ceramic composite materials. A cutting test with a conventional cutting machine under the same condition was also conducted to compare the cutting force. The proposed optimal ultrasonic cutter requires 70% less cutting force than the conventional cutter to cut a ceramic composite material and the cutting surface with the application of the proposed optimal ultrasonic cutter is much cleaner with no crack and delamination than that with the application of the conventional cutter.