Aspiration systems and methods, and expanding-mouth catheters

An aspiration system comprising:

• a catheter including:
• an elongated body defining an inner lumen;
• and
• an expandable member at a distal portion of the elongated body, wherein the expandable member is configured to expand radially outward from a contracted configuration to an expanded configuration;
• a suction source configured to apply a suction force to the catheter to remove fluid from the catheter;
• and
• control circuitry configured to control the expandable member to move between the expanded configuration and the contracted configuration based on an expansion frequency, wherein the control circuitry is configured to determine the expansion frequency based on suction force applied by the suction source to the catheter.