There are many interesting investigation carried out by our group. For details, please read our publication or contact with us directly!

Shock Wave Lithotripsy & Treatment

intraluminal bubble dynamics

We used high-speed imaging to capture the intraluminal bubble dynamics induced by lithotripsy shock waves and also simulate this phenomenon using the finite element method. The significant dilation to the vessel wall is one of the reason of shock wave-induced vessel rupture and renal injury.

improved technologies

We have developed several innovative technologies to improve the performance of shock wave lithotripsy, stone fragmentation effiicency and propensity for renal injury. These technologies include ellipsoidal reflector insert for in-situ pulse superposition, secondary shock wave from piezoelectric annulary array for enhanced bubble collapse, gradually increase the output voltage during the lithotripsy procedure, removal of the secondary bubble cavitation around the discharge electrode, clearance of the residual bubble nuclei in the lithotripter field for effective acoustic wave propagation, dynamically splitting and shifting the lithotripter focus with the progress of stone fragmentation, etc. In vivo studies show the renal injury can be reduced by more than 4 fold while in vitro stone phantom fragmentation is increased by 2.6-fold.

prevention of arthrofibrosis

We firstly applied extracorporeal shock wave treatment (ESWT) to prevent the arthofibrosis during the healing of knee fracture in the rabbit model. Intra-articular adhesions were created in the right knee of the rabbit by cortical bone shaving and subsequent cast immobilization. Arthrofibrosis in the control and ESWT group was evaluated and compared at week 4. Macroscopic score of arthrofibrosis and contracture angle of the control group are significantly higher. Histologically, the apparent gap between patella and tibia, loose connective tissue, and much less density of the blood vessel are found in the ESWT group.This preliminary animal experiment confirmed the effectiveness and safety of suppression arthrofibrosis by shock wave therapy in terms of the macroscopic score of arthrofibrosis, contracture angle of the rightknee, and histological observation. Itshows that shock wave therapy has great potential for the future clinical trial.

High-Intensity Focused Ultrasound (HIFU)

numerical simulation & system calibration

We have carried out a lot of fundamental researches on HIFU. A numerical model using angular spectrum analysis (ASA) and split operator was established to simulate the nonlinear acoustic wave propagation from phased-array transducer in arbitrary sharp through multiple biological layers (i.e., skin, fat, muscle, and then liver for clinical liver ablation). Distributions of higher-order harmonics, absorbed acoustic energy, and temperature elevation in the target are calculated to evaluate the ablation outcomes.

Calibration of HIFU field is also our interest. We first applied fiber optical probe hydrophone (FOPH) in the measurement of HIFU field, developed a mthod of determining the acoustic power using a force probe, and extended the measurement of acoustic intensity using the infrared thermography from the linear range to the nonlinear range.

acculysis

Acculysis means accurately and acoustically lysing the soft tissue. Using a high-speed camera, we have found several important mechanisms of tissue disintegration and bubble cavitation during the exposure of HIFU pulses. A lot of ex vivo tissue samples and preliminary in vivo experiment have been tried with very promising results. It will be developed as a new noninvasive surgical method for solid tumor, benign hyperplasia, blood clot in the vessel occlusion, and the other diseases.

detecting the lesion gap

Utilizing the acoustic radiation force from the therapeutic HIFU pulses, the displacement of lesion and its surround tissue was measured from the recorded RF data. From it the axial shear strain elastography was built. A lesion gap introduces strong axial shear strain in the gap region. Such a strain becomes much weaker when the gap disappears. This monitoring approach is useful in real-time evaluating the outcomes of HIFU ablation.

Manipulation of Drug, Microparticles, & Cells

ultrasound-mediated drug delivery

Ultrasound pulses can be used to overcome the interstitial pressure and enhance the drug delivery diffusion in the solid tumor. We have applied this approach for transsclera drug delivery to retina, transdermal delivery of insulin, etc.

acoustophoresis

Manipulation of microparticle by acoustic field is termed as acoustophoresis. In the standing acoustic field, microparticles can be accumulated at the pressure node effectively no considertion of its chemical and physical properties and without any pre-processing. We developed dual-frequency excitation strategy to flexibly adjust the number and position of pressure nodes.

acoustic nozzle for 3D printing

We developed a novel acoustic nozzle for 3D bio-printing. Cells can be accumulated in the acoustic field and then in the printed samples. Because of the close distance between the printed cells, growth, proliferation, and connection with neighbors becomes much stronger. C2C12 cells that were undergone the acoustic excitation had nuclei oriented densely within ±30° and decreased circularity index by 1.91 fold or significant cell elongation in the printing direction. The printed fiber orientation looks similar to that of human's. the formation of the capillarylike structure in the HUVECs construct was found. The number of nodes, junctions, meshes, and
branches of HUVECs on day 14 was significantly greater with acoustic excitation for the enhanced neovascularization.