Acoustic particle counter for nanoparticles in liquids

An acoustic particle counter for nanoparticles in liquid, comprising:

• at least two sensor units positioned to receive a flow of liquid,
• flow control means for providing a constant, stable rate of flow of the liquid to each sensor unit,
• each sensor unit comprising a measurement cell having inlet and outlet openings for a continuous flow of the liquid through the cell, a transducer module engaged with the measurement cell in position to deliver an acoustic pulse into the liquid as the liquid flows through the cell such that the acoustic pulse is at a known preselected level of intensity and acts on the liquid at a focus zone to cause cavitation in the liquid in the event a particle of a minimum size detectable at that level of intensity is present,
• the at least two said sensor units having the measurement cells of the sensor units arranged in parallel for detecting different-sized particles simultaneously,
• a waveform emitter/receiver module connected to each sensor unit to send a high-frequency, high-voltage signal to the transducer module causing the transducer module to send said acoustic pulse, and also to receive a waveform echo of cavitation in the event of a cavitation in the liquid, thus to detect the cavitation, and
• a microprocessor connected to both waveform emitter/receiver modules to send controlled signals to the waveform emitter/receiver modules each at a known level to cause an acoustic pulse of said preselected level of intensity, and to receive signals from the waveform emitter/receiver modules for analysis and detection of whether a cavitation occurred in the liquid as a result of the acoustic pulse sent.

A method for monitoring purity of a continuously flowing liquid medium by detection of quantity and size of sub-micron particles or impurities present in the liquid medium, comprising:

• providing at least one sensor unit, positioned to receive a flow of the liquid medium, the sensor unit comprising a measurement cell having inlet and outlet openings providing continuous flow of the liquid medium through the cell, and a transducer module engaged with the measurement cell in position to deliver an acoustic pulse into the liquid as the liquid flows through the cell,
• providing a waveform emitter/receiver module connected to the sensor unit for sending a high-frequency, high-voltage signal to the transducer module causing the transducer module to send said acoustic pulse, and also to receive a waveform echo of cavitation in the event of a cavitation in the liquid, thus to detect the cavitation,
• controlling the flow of liquid medium through the measurement cell from upstream of the cell to provide a constant, stable pressure and rate of flow of the liquid medium through the measurement cell of the sensor unit, with essentially constant pressure,
• with a single controller including a microprocessor, the controller being connected to the waveform emitter/receiver module, sending a controlled signal to the waveform emitter/receiver module at known intensity level to cause delivery of an acoustic pulse of preselected intensity into the liquid as the liquid flows through the cell such that the acoustic pulse acts on the liquid at a focus zone to cause cavitation in the liquid in the event a particle is present and a cavitation event in the cell causes an echo which is detected by the waveform emitter/receiver, and
• at the controller receiving signals from the waveform emitter/receiver module for analysis and detection of whether a cavitation occurred in the liquid at the cell as a result of the acoustic pulse sent, to indicate presence of particles of particular size.

A method for monitoring purity of a continuously flowing liquid medium by detection of quantity and size of sub-micron particles or impurities present in the liquid medium, comprising:

• providing at least two sensor units, positioned to receive a flow of the liquid medium, each sensor unit comprising a measurement cell having inlet and outlet openings providing continuous flow of the liquid medium through the cell, and a transducer module engaged with the measurement cell in position to deliver an acoustic pulse into the liquid as the liquid flows through the cell,
• providing a waveform emitter/receiver module connected to each sensor unit for sending a high-frequency, high-voltage signal to the transducer module causing the transducer module to send said acoustic pulse, and also to receive a waveform echo of cavitation in the event of a cavitation in the liquid, thus to detect the cavitation,
• controlling the flow of liquid medium through the measurement cell from upstream of the cell to provide a constant, stable pressure and rate of flow of the liquid medium through the measurement cell of the sensor unit, with essentially constant pressure,
• with a single controller including a microprocessor, the controller being connected to the waveform emitter/receiver modules, sending a controlled signal to the waveform emitter/receiver modules at known intensity level to cause delivery of an acoustic pulse of preselected intensity into the liquid as the liquid flows through the cell such that the acoustic pulse acts on the liquid at a focus zone to cause cavitation in the liquid in the event a particle is present and a cavitation event in the cell causes an echo which is detected by the waveform emitter/receiver,
• at the controller receiving signals from the waveform emitter/receiver module for analysis and detection of whether a cavitation occurred in the liquid at the cell as a result of the acoustic pulse sent, to indicate presence of particles of particular size, and
• the at least two said sensor units being in parallel, controlled by the single controller, and detecting particles of different sizes with the at least two sensor units by providing acoustic pulses of different known intensities in the multiple sensor units so as to cause cavitation events responsive to particles of different minimum sizes.