Methods and apparatuses for predicting and using one or more resonance frequencies for efficient operation of an acoustofluidic cavity

A method of predicting one or more resonance frequencies for efficient operation of an acoustofluidic cavity, such as a channel, in an acoustofluidic device, the method comprising the steps of

• i. filling the cavity with a first liquid;
• ii. obtaining a first impedance spectrum by measuring the electrical impedance of an ultrasound transducer connected to the acoustofluidic device as the transducer is driven at a range of frequencies to supply ultrasound energy to the acoustofluidic device with the first liquid filling the cavity;
• iii. filling the cavity with a second liquid, wherein the second liquid differs from the first liquid in at least one acoustophysical property
• iv. obtaining a second impedance spectrum by measuring the electrical impedance of the ultrasound transducer as the ultrasound transducer is driven at the range of frequencies to supply ultrasound energy to the acoustofluidic device with the second liquid filling the cavity;
• and
• v. predicting the one or more resonance frequencies for efficient operation of the acoustofluidic cavity by comparing the first impedance spectrum and the second impedance spectrum and selecting the one or more frequencies wherein an absolute value of the difference between the first and second impedance spectra, normalized by the absolute value of one of them, is largest.

An apparatus for predicting one or more resonance frequencies for efficient operation of an acoustofluidic cavity in an acoustofluidic device, the apparatus comprising:

• a device configured to sequentially fill the acoustofluidic cavity with a first liquid and a second liquid, wherein the second liquid differs from the first liquid in at least one acoustophysical property;
• a drive unit configured to drive an ultrasound transducer connected to the acoustofluidic device at a range of frequencies to supply ultrasound energy to the acoustofluidic device;
• an impedance sensing unit electrically connected to the drive unit and configured to obtain first and second impedance spectra, by measuring the impedance of the ultrasound transducer as it is driven over the range of frequencies, when the cavity is filed with first liquid and the second, respectively;
• and
• a computing device configured to predict one or more resonance frequencies for efficient operation of the acoustofluidic cavity by comparing the first and second impedance spectra and selecting the frequencies where the absolute value of the difference between the first and second impedance spectra, normalized by the absolute value of one of them, is largest.

An apparatus comprising an acoustofluidic device with an acoustofluidic cavity, the apparatus being configured to perform an acoustofluidic operation in the acoustofluidic cavity, wherein the apparatus comprises:

• an ultrasound transducer connected to the acoustofluidic device so as to perform the acoustofluidic operation;
• a device configured to sequentially to fill the acoustofluidic cavity with a first liquid and a second liquid, wherein the second liquid differs from the first liquid in at least one acoustophysical property;
• a drive unit configured to drive an ultrasound transducer connected to the acoustofluidic device at a range of frequencies to supply ultrasound energy to the acoustofluidic device;
• an impedance sensing unit electrically connected to the drive unit and configured to obtain first and second impedance spectra, by measuring the impedance of the ultrasound transducer as it is driven over the range of frequencies, when the cavity is filed with first liquid and the second, respectively;
• and
• a computing device configured to predict one or more resonance frequencies for efficient operation of the acoustofluidic cavity by comparing the first and second impedance spectra and selecting the frequencies where the absolute value of the difference between the first and second impedance spectra, normalized by the absolute value of one of them, is largest;
• wherein the drive unit is electrically connected to the ultrasound transducer, and
• wherein the apparatus is further configured to perform the acoustofluidic operation by one of (a) driving the ultrasound transducer with at least one frequency within 90% to 110% of one or more of the predicted resonance frequencies, and (b) driving the ultrasound transducer with a frequency sweep encompassing a frequency within 90% to 110% of one or more of the predicted resonance frequencies.

A method of predicting one or more resonance frequencies for efficient operation of an acoustofluidic cavity, the method comprising the steps of:

• i. setting the temperature of the acoustofluidic device to a first temperature T1;
• ii. filling the cavity with a first liquid and allowing the liquid to reach the first temperature T1;
• iii. obtaining a first liquid impedance spectrum by measuring the electrical impedance of an ultrasound transducer connected to the acoustofluidic device as the transducer is driven at a range of frequencies to supply ultrasound energy to the acoustofluidic device with the first liquid at the first temperature T1 filling the cavity;
• iv. filling the cavity with a first gas filling and allowing the first gas to reach the first temperature T1;
• v. obtaining a first gas impedance spectrum by measuring the electrical impedance of an ultrasound transducer connected to the acoustofluidic device as the transducer is driven at a range of frequencies to supply ultrasound energy to the acoustofluidic device with the first gas at the first temperature T1 filling the cavity;
• vi. setting the temperature of the acoustofluidic device to a second temperature T2, which second temperature T2 is different from the first temperature T1;
• vii. filling the cavity with a second liquid and allowing the second liquid to reach the second temperature T2;
• viii. obtaining a second liquid impedance spectrum by measuring the electrical impedance of an ultrasound transducer connected to the acoustofluidic device as the transducer is driven at a range of frequencies to supply ultrasound energy to the acoustofluidic device with the second liquid at the second temperature T2 filling the cavity;
• ix. filling the cavity with a second gas and allowing the second gas to reach the second temperature T2;
• x. obtaining a second gas impedance spectrum by measuring the electrical impedance of an ultrasound transducer connected to the acoustofluidic device as the transducer is driven at a range of frequencies to supply ultrasound energy to the acoustofluidic device with the second gas at the second temperature T2 filling the cavity;
• xi. determining a first differential impedance spectrum from the first and the second liquid impedance spectra;
• xii. determining a second differential impedance spectrum from the first and the second gas impedance spectra;
• and
• i. predicting the one or more resonance frequencies for efficient operation of the acoustofluidic cavity by comparing the first and second differential impedance spectra and selecting the one or more frequencies where the first and second differential impedance spectra differ the most.

An apparatus for predicting one or more resonance frequencies for efficient operation of an acoustofluidic cavity in an acoustofluidic device, the apparatus comprising:

• a device configured to selectively provide a first liquid, a second liquid, a first gas, and a second gas filling the acoustofluidic cavity;
• a temperature control device configured to selectively control the temperature of the acoustofluidic device to a first temperature T1 and a second temperature T2, respectively;
• a drive unit configured to drive an ultrasound transducer connected to the acoustofluidic device at a range of frequencies to supply ultrasound energy to the acoustofluidic device;
• an impedance sensing unit electrically connected to the drive unit and configured to obtain first and second liquid impedance spectra, and first and second gas impedance spectra, by measuring the impedance of the ultrasound transducer as it is driven over the range of frequencies, when the first liquid and the second liquid, respectively, and the first gas and the second gas, respectively, fill the cavity at the first temperature T1 and the second temperature T2, respectively;
• and
• a computing device configured to determine first and second differential impedance spectra, and further configured to predict the one or more resonance frequencies for efficient operation of the acoustofluidic cavity, by comparing the first and second differential impedance spectra and selecting the one or more frequencies where the first and second differential impedance spectra differ the most.

A system for performing an acoustofluidic operation in an acoustofluidic cavity in an acoustofluidic device, the system comprising:

• an ultrasound transducer connected to the acoustofluidic device;
• a device configured to selectively provide a first liquid, a second liquid, a first gas, and a second gas filling the acoustofluidic cavity;
• a temperature control device configured to selectively control the temperature of the acoustofluidic device to a first temperature T1 and a second temperature T2, respectively;
• a drive unit configured to drive an ultrasound transducer connected to the acoustofluidic device at a range of frequencies to supply ultrasound energy to the acoustofluidic device;
• an impedance sensing unit electrically connected to the drive unit and configured to obtain first and second liquid impedance spectra, and first and second gas impedance spectra, by measuring the impedance of the ultrasound transducer as it is driven over the range of frequencies, when the first liquid and the second liquid, respectively, and the first gas and the second gas, respectively, fill the cavity at the first temperature T1 and the second temperature T2, respectively;
• and
• a computing device configured to determine first and second differential impedance spectra, and further configured to predict the one or more resonance frequencies for efficient operation of the acoustofluidic cavity, by comparing the first and second differential impedance spectra and selecting the one or more frequencies where the first and second differential impedance spectra differ the most;
• wherein the drive unit is electrically connected to the ultrasound transducer;
• and
• wherein the system is further configured to perform the acoustofluidic operation by driving the ultrasound transducer with one of (a) at least one frequency within 90% to 110% of one or more of the predicted resonance frequencies, and (b) a frequency sweep encompassing a frequency within 90% to 110% of one or more of the predicted resonance frequencies.