Benthowave Instrument Inc.

BENTHOWAVE INSTRUMENT INC. Acoustic Transducer & System 

High Intensity Focused Ultrasound (HIFU) Transducer

HIFU TransducerHIFU TransducerHIFU TransducerHigh Intensity Focused Ultrasound (HIFU) TransducerHIFU TransducerHIFU TransducerHIFU Transducer

Benthowave's high intensity focused ultrasound transducers consist of bowl aperture with focal point and curved aperture of cylindrical plate with focal line for thermal, chemical and high-stress uses in nonlinear underwater acoustics: cavitation, streaming, sonic processes and HIFU R&D.
If you need information of BII HIFU transducers to determine their MRI compatibility or safety, please contact BII.

To support HIFU R&D, BII provides customized designs on geometric focus, Fresnel number, focal diameter/length/intensity.

Focal Intensity: (Electric Power from Power Amplifier) * Efficiency * (Focal Intensity per Acoustic Power)
Acoustic Focus ZF: 1. Bowl aperture: the distance from acoustic focus to the center of concave face of the transducer.
2. Curved aperture of cylindrical plate: the vertical distance from acoustic focus to the concave face of the transducer.
ZT: The vertical distance from acoustic focus to the imaginary plane of end face of the transducer housing.
Focal Length: 1. Bowl aperture: focal Depth or distance between -3dB points of the focal zone along acoustic axis perpendicular to bowl.
2. Curved aperture of cylindrical plate: distance between -3dB points of the focal zone along geometrical axis paralleling to curved cylindrical plate.
Focal Diameter: Bowl aperture: the diameter of the beam at -3dB points .
Focal Width: Curved aperture of cylindrical plate: the width of the beam at -3dB points perpendicular to focal length.
Acoustic Axis: Symmetric line normal to the concave face of the transducer.
Acoustic Axial Distance:  The distance between the point on acoustic axis to the center of concave face of the transducer.  
Normalized Pressure: The ratio of the pressure on Acoustic Axis to the pressure at geometric focus.
Drive Power: Electric power delivered to a HIFU transducer from power amplifier and/or impedance matching network.

Optional mounting parts are available for installation on portable-mounting apparatus, submersibles, pipe, tank or vessel.
An impedance matching & tuning network is optional to provide correct impedance match to load requirements of power amplifiers.

Technical notes
The cable has adverse effects on the transducer performances in high frequency range. The longer the cable is, the worse the adverse effects on the transducer performance is. When you place order, please specify the shortest cable length acceptable to your project.
If you use long cable (comparing to electromagnetic wavelength) in high frequency range, you shall have an impedance matching unit built inside the transducer to match cable impedance such as 50Ω RG58 coax or 67Ω shielded cable.

BII-7650    High Intensity Focused Ultrasound (HIFU) Transducer

Benthowave stocks following cables:  
Cable Nominal Impedance
RG58 Coax 50 Ω
Shielded Cable, Two Conductors 67 Ω
Suggested Application  
Cavitation/Streaming/Acoustic Wave Interaction
High Frequency Ultrasound Energy Sources
Sonic Processing/Testing/Analysis
Thermal/Mechanical/Chemical/Biological Effects
Sonic Radiation in Sonochemistry/Material Processing/Sonoluminescence
Anti-algae & Anti-bacteria, Fluid Dynamics, Nonlinear Acoustics
Focused Sound Sources for HIFU R&D
High Intensity:5000W/cm^2 100kHz to 2.0MHz, and the Odd Harmonics
Related Products  
BII-5100 High Efficiency Switching Power Amplifier BII-5110 High Efficiency Switching Power Amplifier
BII-5040 Linear Power Amplifier BII-5120 Linear and Switching Power Amplifier


How to calculate the focal intensity?
As an example, consider a power amplifier of 60 Watts output power to drive BII-7653/2000 at 2MHz, the peak intensity at center of the focus = 60W * 0.5 * 175W/(W*cm^2) or 5250 W/cm^2. Depending on the liquid or subject properties, cavitation might occur in regions between the transducer and the focus, so the actual intensity at focus might be much reduced.
Testing before shipment: BII carries out the cavitation test in water to HIFU transducers.
: The Focal Intensity, Focal Diameter and Focal Length in the specs are tested with low intensity sound level at BII or are calculated with electrical and physical parameters of the transducers. BII DOES NOT GUARANTEE THEIR ACCURACY. To get accurate data of these parameters, the buyer shall have the transducer tested at the buyer's cost by National Metrology Institutes or other organizations who provide calibration services.
(Focal Point)
Focal Intensity
per Acoustic Power
Efficiency Aperture Focal
Drive Power
BII-7651Q/300 0.3 7.1 0.6 Bowl 3.55 11.85 17.5 10.5 100 Φ42x30
BII-7651Q/500 0.5 14.0 0.6 Bowl 2.13 7.11 19.5 12.5 80 Φ42x30
BII-7651Q/1000 1.0 78.6 0.5 Bowl 1.07 3.56 20.5 13.5 60 Φ42x30
BII-7651Q/2000 2.0 314.4 0.5 Bowl 0.53 1.78 21 14.0 50 Φ42x30
BII-7651H/300 0.3 4.8 0.60 Bowl 4.29 17.3 25.0 18.7 100 Φ48x30
BII-7651H/500 0.5 13.5 0.60 Bowl 2.58 10.38 27.0 20.7 80 Φ48x30
BII-7651H/1000 1.0 53.8 0.50 Bowl 1.29 5.19 29.5 23.2 60 Φ48x30
BII-7651H/2000 2.0 215.4 0.50 Bowl 0.64 2.60 30.0 23.7 50 Φ48x30
BII-7652/200 0.2 3.0 0.60 Bowl 5.51 18.97 27.5 17.4 200 Φ60x35
BII-7652/300 0.3 6.6 0.60 Bowl 3.67 12.64 30.0 20.0 150 Φ60x35
BII-7652/500 0.5 18.4 0.50 Bowl 2.20 7.60 32.0 22.0 120 Φ60x35
BII-7652/1000 1.0 73.6 0.50 Bowl 1.10 3.80 32.5 22.4 90 Φ60x35
BII-7652/2000 2.0 294.6 0.50 Bowl 0.55 1.90 33.0 23.0 75 Φ60x35
BII-7653/100 0.1 0.6 0.60 Bowl 11.2 56.5 56.0 41.6 300 Φ89x45
BII-7653/150 0.15 1.3 0.60 Bowl 7.46 37.68 56.0 41.6 300 Φ89x38
BII-7653/200 0.2 2.7 0.60 Bowl 7.00 32.00 43.2 34.5 200 Φ89x38
BII-7653/300 0.3 4.0 0.50 Bowl 4.80 21.00 48.0 39.0 160 Φ89x38
BII-7653/500 0.5 11.0 0.50 Bowl 3.00 13.00 51.0 42.0 120 Φ89x38
BII-7653/1000 1.0 44.0 0.50 Bowl 1.50 6.00 52.5 43.5 100 Φ89x38
BII-7653/2000 2.0 175.0 0.50 Bowl 1.00 3.00 53.0 44.0 80 Φ89x38
BII-7654/100 0.1 0.34 0.60 Bowl 15 101.4 100.0 86.6 500 Φ114x45
BII-7654/150 0.15 0.75 0.60 Bowl 10.0 67.60 100.0 86.6 500 Φ114x38
BII-7654/200 0.2 1.53 0.60 Bowl 7.70 36.60 88.0 74.6 350 Φ114x38
BII-7654/300 0.3 3.43 0.50 Bowl 5.10 24.40 92.5 79.1 300 Φ114x38
BII-7654/500 0.5 9.54 0.50 Bowl 3.06 14.64 95.5 82.1 200 Φ114x38
(Focal Line)
Focal Intensity
per Acoustic Power
Efficiency Aperture Focal
Drive Power
BII-7656/500 0.5 2.5 0.60 Curved Plate 2.6 28.3 17 11.1 250 36x36x25
BII-7656/1000 1 5.0 0.50 Curved Plate 1.3 28.3 17 11.1 250 36x36x20
BII-7656/2000 2 10.0 0.50 Curved Plate 0.65 28.3 17 11.1 250 36x36x20
BII-7657/300 0.3 1.2 0.60 Curved Plate 4.3 36.8 23 15.5 400 46x46x40
BII-7657/500 0.5 2.0 0.60 Curved Plate 2.6 36.8 23 15.5 350 46x46x35
BII-7657/1000 1 4.0 0.50 Curved Plate 1.3 36.8 23 15.5 350 46x46x30
BII-7657/2000 2 7.8 0.50 Curved Plate 0.65 36.8 23 15.5 300 46x46x30
BII-7658/300 0.3 0.8 0.60 Curved Plate 4.3 50.8 35.5 24.0 350 62x58x45
BII-7658/500 0.5 1.3 0.60 Curved Plate 2.6 50.8 35.5 24.0 350 62x58x40
BII-7658/1000 1 2.6 0.50 Curved Plate 1.3 50.8 35.5 24.0 400 62x58x40
BII-7659/200 0.2 0.4 0.60 Curved Plate 6.5 50.8 48.0 33.0 500 80x58x45
BII-7659/300 0.3 0.6 0.60 Curved Plate 4.3 50.8 48.0 33.0 500 80x58x40
BII-7659/500 0.5 1.0 0.60 Curved Plate 2.6 50.8 48.0 33.0 500 80x58x40
fs Tolerance: ±5% Typical
Third Harmonic: 2.9fs ~ 3.2fs
Focal Intensity: Focal Intensity=(Electric Power from Power Amplifier) * Efficiency * (Focal Intensity per Acoustic Power)
Cable Length: 1. Default: 0.3m
2. Custom: up to 30m
Matching & Tuning: BII-6010 Impedance Matching & Tuning: 2Ω to 16Ω, 50Ω, 60Ω, 75Ω, 100Ω, etc..., Order Separately. Customized to optimum load of the power amplifier, append IM to part number for integrating BII-6010 in HIFU transducer.
Note: BII's impedance matching and tuning can ONLY be implemented at a specific frequency, generally, which is fundamental resonant frequency of the transducer. Buyers shall specify the frequency when ordering if buyer needs customized frequency of impedance matching and tuning.
Power Amplifier: BII-5000 Series Power Amplifier, Order Separately, or Third-party's power amplifiers such as 50Ω RF power amplifiers.
Operating Depth: 50m underwater, Maximum
Temperature Sensor: 1. Default: No built-in temperature sensor.
2. Built-in temperature sensor. When ordering, append TS to part number for integrating a temperature sensor in the transducer. Click Temperature Characteristics for more information.
Mounting Options: 1. Default: Free Hanging (FH)
2. Free-hanging with Male Underwater Connector (FHUWC)

3. Thru-hole Mounting with Single O-ring (THSO)
4. Thru-hole Mounting with Double O-ring (THDO)
5. Bolt Fastening Mounting (Stainless Steel): (BFMSS)
6. End-face Mounting:  (EFM)
Transducer and Hydrophone Mounting for more detailed information on mounting/installation.
Cable: 1. 67 ohms Shielded cable with Two Conductors (SC)
2. 50 ohms RG58 Coax (RG58)
Connector: 1. Default: Wire Leads (WL)
2. 50Ω BNC Male (BNC)
    Warning: It is buyer's sole responsibility to make sure that the (female) BNC shield of the signal source is firmly
    grounded for operating safety before hooking up transducer to the signal source. Coax with BNC is not intended for
    hand-held use at voltages above 30Vac/60Vdc
3. MIL-5015 Style (5015)
4. Underwater Mateable Connector (UMC)
5. Custom (Custom)
Operating Frequency: Besides standard operating frequency fs, the transducers can also operate at odd harmonic 3fs with lower power efficiency (about 20% to 30% lower).
If the transducer is used at 3fs, an optional impedance matching & tuning network at 3fs shall be ordered instead of the network at fs.
Cooling Transducer: To avoid overheating the HIFU transducer, shutting down power to cool down HIFU transducers is a MUST. For example, driving HIFU 1 minute, shut down power 2 minutes for the transducer to cool down in liquid/water by itself.
Remove Air Bubbles
on Radiation Surface:
To increase power efficiency, the air bubbles on transducer radiation face developed during operation must be removed with soft cloth before driving the transducer. An flashlight is a useful aid to check the situation of the transducer surface underwater. It is a good routine to rub the transducer radiation surface lightly with soft cloth before operating the transducer each time. Do NOT touch the water/liquid and transducer when the system is powered.
Operating Temperature: -10°C to +60°C
Storage Temperature: -40°C to +60°C
How to Order: Click How to Order.
Transducer Wiring: Click Transducer Wiring for detailed wiring information.
General Operating Guide of BII HIFU Transducer
To produce the cavitation in liquids, please choose carefully the liquid (surface tension, viscosity, temperature), hydrostatic pressure, pulse length, operating frequency and driving voltage level or driving power. As a general guide, the cavitation threshold of the liquid increases as the operating frequency increases.
Driving HIFU Transducer Phenomenon on Water Surface at Room Temperature: Mist, Fog and Fountain.
6 to 10 watt Fountain occurs; Mist and Fog start to occur.
15 to 60 watt Strong Fountain, Mist and Fog.
Cool down transducer Driving HIFU 1 minute, shut down 2 minutes.
Remove air bubbles
on radiation surface
Rub the radiation surface lightly with soft cloth in water before driving HIFU transducer each time.
Warning: Do NOT touch water and transducer when the system is powered.
BII-HIFU Transducer Testing in Water at BII Laboratory
Electric Driving Power to BII HIFU Transducer under Test: 60 Watt.
Phenomenon: Strong Mist, Fog and Fountain.
Download HIFU video (*.MPG format):  Click HIFU Video 1, HIFU Video 2, HIFU Video 3 to download.
Note: a media player is needed to play the videos.

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