[0008] Clause 4: In some examples of the aspiration system of any of clauses 1-3, the flow oscillator is configured to generate vibrations capable of haptic detection by a human for flow in a first direction and generate vibrations that are not capable of haptic detection by a human for flow in a second direction. [0009] Clause 5: In some examples of the aspiration system of any of clauses 1-4, the flow oscillator is configured to oscillate the flow of the fluid above an oscillation threshold in a first flow direction and not oscillate the flow of the fluid above the oscillation threshold in a second flow direction. [0010] Clause 6: In some examples of the aspiration system of any of clauses 1-5, each of the fluid inlet and the fluid outlet are configured to couple to aspiration tubing. [0011] Clause 7: In some examples of the aspiration system of clause 6, the flow oscillator further comprises at least one channel, and wherein a cross-sectional area of the at least one channel is greater than a cross-sectional area of an inner lumen of the aspiration tubing. [0012] Clause 8: In some examples of the aspiration system of any of clauses 1-7, the flow oscillator further comprises defines at least one channel, and wherein an inner diameter of the at least one channel is greater than an inner diameter of the catheter. [0013] Clause 9: In some examples of the aspiration system of any of clauses 1-8, the flow oscillator further comprises: at least one primary channel configured to pass a majority of the flow of the fluid; and at least two secondary channels each configured to divert a portion of the flow of the fluid from a downstream portion of the at least one primary channel to an upstream portion of the at least one primary channel. [0014] Clause 10: In some examples of the aspiration system of any of clauses 1-9, the aspiration system further comprises a pressure sensor mechanically coupled to the fluid flow sensor and configured to detect vibrations from the fluid flow sensor indicating flow of the fluid through the fluid flow sensor. [0015] Clause 11: In some examples of the aspiration system of clause 10, the pressure sensor is configured to communicatively couple to a notification system configured to generate a notification in response to detecting the flow of the fluid. [0016] Clause 12: In some examples of the aspiration system of any of clauses 1-1 1, the fluid oscillator is configured to generate vibrations having a frequency of about 15 hertz to about 30 hertz at a flow rate of the fluid of about 3 milliliters per second to about 5 milliliters per second.