System and method for ultrasonic measuring of particle properties
Devices, systems and methods for measuring and detecting properties of a variety of particles or cells in suspension. Properties, such as, for example, velocity of particles, concentration and/or size may be measured according to the methods of the invention. Acoustic energy may be introduced to a focal zone and narrow band interrogating signals may be used. The acoustic energy may cause movement or streaming of the fluid or suspension. The acoustic streaming may allow a Doppler effect measurement without any other source of velocity.
1. A system for measuring properties of particles in a suspension, the system comprising:
a transducer to transmit an ultrasonic signal toward the particles and to receive a return signal reflected or backscattered from the particles; and
a processor to generate a power spectrum by processing the return signal to obtain properties of the particles;
wherein the processor is to estimate the energy contained in off-peak bins of the power spectrum of the return signal, and wherein estimating the backscattered energy comprises summing the power of a plurality of bins.
2. The system of claim 1 , wherein the ultrasonic signal induces streaming of the fluid containing the particles within a focal zone, and wherein the focal zone comprises a volume where the majority of backscatter from the particles is generated.
3. The system of claim 1 , wherein a single transducer is used both to direct the signal to the particles and to receive the backscattered return signal.
4. The system of claim 1 , wherein said ultrasonic signal is having a number of identical single frequency tone bursts of at least 10 cycles and wherein the ultrasonic signal further comprising introduction of gaps between the identical single frequency tone bursts, and wherein the transducer is to receive the return signal during the gaps between the single frequency tone bursts.
5. The system of claim 1 , wherein said ultrasonic signal is having a number of identical single frequency tone bursts of at least 10 cycles and wherein the single frequency is at a range of between 7 MHz and 20 MHz.
6. The system of claim 1 wherein the properties measured comprise velocity, size of the particles, concentration, viscosity of the suspension or a combination thereof.
7. The system of claim 1 , wherein the processor is to apply a several million point Fast Fourier Transform algorithm to the return signal to obtain a high resolution power spectrum, or wherein the processor is to apply a narrow band filter to the return signal to obtain a power spectrum.
8. The system of claim 1 , wherein the processor is to display the power spectrum of the return signal in a frequency domain of narrow bin size, and wherein the bin size is less than 200 Hz.
9. The system of claim 1 , wherein said ultrasonic signal is having a number of identical single frequency tone bursts of at least 10 cycles and wherein the transducer is to receive the return signal during intervals between the tone bursts of the ultrasonic signal.
10. The system of claim 1 , further comprising a unit to induce particle motion by introduction of bulk flow, by stirring or by a combination thereof.
11. The system of claim 1 , wherein the transducer is positioned outside the fluid volume and the interrogating acoustic power and the return signal associated with said transducer propagates through the wall of the test vessel or through an acoustic window in said wall so that there is no contact with the suspension.
12. The system of claim 1 , wherein said signal induces streaming of said suspension.
13. A system for measuring properties of particles in a suspension, the system comprising:
a transducer to transmit an ultrasonic signal toward the particles and to receive a return signal reflected or backscattered from the particles; and
a processor to generate a power spectrum by processing the return signal to obtain properties of the particles;
wherein the velocity of particle motion induced by streaming is measured by location of a power spectrum peak at a frequency representing the Doppler shift due to that velocity.
14. A system for measuring properties of particles in a suspension, the system comprising:
a transducer to transmit an ultrasonic signal toward the particles and to receive a return signal reflected or backscattered from the particles; and
a processor to generate a power spectrum by processing the return signal to obtain properties of the particles;
wherein the velocity of particle motion induced by streaming is measured by location of a power spectrum peak at a frequency representing the Doppler shift due to that velocity; and
wherein the diameter of the particle is determined by the velocity of the particle.