above, a change in fluid flow during an aspiration procedure may indicate to a clinician operating aspiration system 10 whether a condition of the aspiration procedure has been met. For example, absence of, presence of, and/or changes in fluid flow may indicate to a clinician operating aspiration system 10 that a condition related to engagement of catheter 12 with a thrombus has occurred. Fluid flow sensor 16 is configured to provide the clinician with an indication of the presence or absence of fluid flow through an inner lumen of catheter 12, where this indication may be detected by the clinician without the clinician diverting her vision from another aspect of the aspiration procedure, such as an x-ray screen. 

[0058] Fluid flow sensor 16 includes a fluid inlet 22 configured to receive fluid from catheter 12, either directly or indirectly through other tubing and/or other structures such as switch 14. In some examples, fluid inlet 22 may be configured to attach to aspiration tubing 28, switch 14, or another fluid conduit upstream of fluid flow sensor 16. Fluid flow sensor 16 includes a fluid outlet 24 configured to discharge the fluid received from catheter 12. For example, fluid outlet 24 may be configured to attach to aspiration tubing 30, pump 18, or another fluid conduit downstream of fluid flow sensor 16. Each of fluid inlet 22 and fluid outlet 24 may include other components for attaching to other components of system 10, such as tubing connectors. In some examples, each of fluid inlet 22 and fluid outlet 24 are configured to couple to aspiration tubing, such as aspiration tubing 26, 28, or 30. 

[0059] Fluid flow sensor 16 may be positioned in aspiration system 10 at a variety of locations. For example, while shown coupled between fluid pump 18 and fluid switch 14, fluid flow sensor 16 may be positioned at any suitable location between fluid pump 18 and a proximal end of catheter 12, such that fluid flow sensor 16 may be in a sterile field. In some examples, fluid flow sensor 16 may be removeable from aspiration system 10. For example, a clinician may want to remove fluid flow sensor 16 from aspiration system 10. In this instance, the clinician may decouple fluid inlet 22 and/or fluid outlet 24 from a respective aspiration tubing 28 and/or aspiration tubing 30 and link aspiration tubing 28 directly to aspiration tubing 30, such as through an adapter (not shown). In this way, fluid flow sensor 16 may be selectively incorporated into aspiration system 10. In some examples, fluid inlet 22 and/or fluid outlet 24 may include structures for restricting flow during decoupling of fluid flow sensor 16, such as coupling adapters that remain coupled to aspiration tubing 28 and/or 30, such that flow oscillator 20 may be removable from fluid inlet 22 and/or fluid outlet 24. In this way, flow oscillator 20 may be removed from 

