infusion state) and subsequently draw fluid from a site of catheter 12, such as saline and/or blood, from catheter 12 (e.g., an aspiration state) into discharge fluid reservoir 34. As another example of bidirectional operation, fluid pump 18 may be configured to simultaneously pump aspiration fluid from aspiration fluid reservoir 32 to catheter 12, such as through an outer catheter (not shown in FIG. 1) within which catheter 12 is positioned or through a lumen of a multi-lumen catheter 12, and draw fluid from catheter 12 (e.g., through an inner lumen of catheter 12 if used with an outer catheter or through a different lumen of a multi-lumen catheter 12) into discharge fluid reservoir 34. 

[0055] In some examples, aspiration system 10 may include fluid switch 14 to control fluid flow through aspiration system 10. Fluid switch 14 may be configured to start and stop fluid flow from catheter 12 to fluid pump 18 (or in the opposite direction). For example, fluid flow switch 14 may have an “open” position corresponding to flow of fluid through fluid switch 14 and a “closed” position corresponding to no flow of fluid through fluid switch 14. A variety of switching mechanisms may be used for fluid flow switch 14 including, but not limited to, valves, sliders, and the like. In some example, fluid switch 14 may be configured for unaided operation by a clinician. For example, a mechanism of blocking fluid flow through fluid flow switch 14 may be directly operable by a mechanical force provided by the clinician. 

[0056] In some examples, fluid switch 14 may be ergonomically positioned such that a clinician operating aspiration system 10 may control flow of fluid using fluid switch 14 and receive feedback from fluid flow sensor 16 using a single hand. For example, a clinician may guide catheter 12 through vasculature of a patient using a first hand, and control and sense fluid flow with a second hand. In this way, aspiration system 10 may enable control of aspiration system 10 by a single clinician and without a clinician diverting her focus while positioning catheter 12. In some examples, fluid flow switch 14 may be less than about ten centimeters from fluid flow sensor 16. For example, fluid switch 14 may be coupled to flow oscillator 20 by aspiration tubing 28 that is less than or equal to ten centimeters. In some examples, a clinician operating aspiration system 10 may hold both fluid switch 14 and fluid flow sensor 16 in one hand at a same time, such that fluid switch 14 is positioned at her thumb for control of a switch of fluid switch 14 and fluid flow sensor 16 is positioned in her palm for haptic feedback from fluid flow sensor 16. 

[0057] Aspiration system 10 includes fluid flow sensor 16. Fluid flow sensor 16 may be configured to provide haptic feedback of fluid flow from catheter 12. As explained 

