Adaptive Focused Acoustics® (AFA) is an advanced acoustic technology enabling the mechanical processing of samples by Focused-ultrasonicators. AFA employs highly controlled bursts of focused high-frequency acoustic energy to efficiently and reproducibly process samples in a temperature-controlled and non-contact environment. The very high-frequency ultrasound utilized in AFA results in a wavelength of only a few millimeters, enabling the acoustic energy to be focused into a discrete zone within a sample vessel. This focused and efficient delivery requires a minimal amount of energy input avoiding the adverse effects of excess energy such as damaging heat, experimental variability, and sample over-processing typical of ordinary sonicators.
Sample processing with AFA ultrasonic energy is accomplished by controlling the creation and collapse of millions of cavitation bubbles within the sample vessel. Fluctuations in pressure occur as acoustic energy passes through an aqueous medium forming small cavities (or bubbles) in the regions of relative low pressure. The cavitation bubbles can oscillate or grow to a critical size and then collapse. The oscillation and collapse of the cavitation bubbles generates acoustic microstreaming which creates hydrodynamic shear stress in the sample. AFA Focused-ultrasonicators provide exquisite control of the acoustic bursts delivered to a sample. The tuning of peak incident power, duration, and duty factor, controls the microstreaming and in turn the generation of shearing forces.
AFA can be tuned to process samples in a variety of applications, from low-power gentle mixing of solutions and protein extraction, to higher-power applications such as DNA fragmentation, liposome formation, and the creation of nanosuspensions.
High Frequency Acoustics
AFA delivers high frequency ultrasonic acoustic energy, which is in the same acoustic range used in medical applications, such as diagnostic imaging and lithotripsy. AFA operates at a frequency of 500 kHz and provides several advantages in a laboratory setting:
AFA has a shorter wavelength – scaled to the size of biologic samples
AFA is focused – less energy is required to achieve a given process
Higher frequency sound waves have shorter wavelengths, and reciprocally, low-frequency sound waves have longer wavelengths. The short wavelength acoustic energy delivered by AFA (approximately 3 mm) is scaled to the size of biological samples and enables precise focusing within a discrete zone enabling highly controlled sample preparation. Ordinary probe and bath sonicators operate at a frequency of 10 to 30 kHz, which is on the cusp of the audible (sonic) range. At this frequency, the wavelength is approximately 100 mm which is larger than a typical sample vessel (~10 to 100 mm) and is unable to be focused into a sample vessel. AFA is more reproducible because it is more closely scaled to the vessel size; therefore, the entire acoustic wave passes through the vessel, repeatedly delivering the same dose of energy.
Covaris provides tools and technologies to improve pre-analytical sample preparation, enable novel drug formulations, and manage compounds in the drug discovery process.