[0017] Clause 13: In some examples of the aspiration system of any of clauses 1-12, the fluid oscillator is configured to increase a magnitude of the vibrations in response to an increase in a flow rate of the fluid through the fluid oscillator. [0018] Clause 14: In some examples of the aspiration system of any of clauses 1-13, the fluid oscillator is configured to increase a frequency of the vibrations in response to an increase in a flow rate of the fluid through the fluid oscillator. [0019] Clause 15: In some examples of the aspiration system of any of clauses 1-14, the aspiration system further comprises a fluid switch configured to start and stop the flow of the fluid through the fluid oscillator. [0020] Clause 16: In some examples of the aspiration system of clause 15, the fluid switch is upstream of the fluid flow sensor. [0021] Clause 17: In some examples of the aspiration system of clause 16, the fluid switch is coupled to the flow oscillator by less than ten centimeters aspiration tubing. [0022] Clause 18: In some examples of the aspiration system of any of clauses 1-17, the catheter is upstream of the fluid flow sensor, the system further comprising a fluid pump downstream of the flow sensor and configured to generate a suction through the catheter. [0023] Clause 19: In some examples of the aspiration system of any of clauses 1-18, the flow oscillator is coated with at least one of an anti-thrombogenic material or a lubricious material. [0024] Clause 20: In one example, a fluid flow sensor comprises: a fluid inlet configured to receive fluid from a catheter; an inlet connector proximate to the fluid inlet and configured to couple to at least one of aspiration tubing or a fluid switch; a fluid outlet configured to discharge the fluid; an outlet connector proximate to the fluid outlet and configured to couple to aspiration tubing; and a flow oscillator configured to oscillate flow of the fluid through the fluid flow sensor to generate flow-induced vibrations. [0025] Clause 21: In some examples of the fluid flow sensor of clause 20, the flow oscillator further comprises: a flow diverting portion configured to oscillate the flow of the fluid between the fluid inlet and the fluid outlet to generate an oscillating pressure differential; and an oscillating portion downstream of the flow diverting portion and configured to oscillate in response to the oscillating pressure differential. [0026] Clause 22: In some examples of the fluid flow sensor of clause 20 or 21, the flow oscillator is configured to oscillate the flow of the fluid above an oscillation