[0062] Flow oscillator 20 further comprises at least one channel or chamber configured to pass fluid from sensor inlet 22 to sensor outlet 24. In some examples, a cross-sectional area of the at least one channel may be greater than a cross-sectional area of aspiration tubing 28. For example, flow oscillator 20 may create a pressure drop for fluid entering the at least one channel. Additionally or alternatively, in some examples, an inner diameter of the at least one channel may be greater than an inner diameter of the lumen of catheter 12 from which fluid flow sensor 16 receives fluid. 

[0063] Flow oscillator 20 may be manufactured from any suitable material including, but not limited to, polymers, metals, and the like. In some examples, flow oscillator 20 is manufactured using injection molding or three-dimensional (3D) printing. For example, as will be discussed further below, flow oscillator 20 may be configured to oscillate fluid flow through fluid flow sensor 16 without moving parts. As such, inexpensive manufacturing techniques such as injection molding and 3D printing may be used to manufacture flow oscillator 20. 

[0064] In some examples, fluid flow sensor 16 includes a pressure sensor configured to detect flow of the fluid. For example, while fluid flow sensor 16 may be configured to produce flow-induced vibrations, amplification, recording, or some other post-processing of the vibrations may be desired. As such, the pressure sensor may be kinetically coupled to (i.e., coupled to receive kinetic energy from) flow oscillator 20 of fluid flow sensor 16, such that vibrations from flow oscillator 20 may be detected by the pressure sensor. In some examples, the pressure sensor is communicatively coupled to a notification system configured to generate a notification in response to detecting the flow of the fluid. For example, a pressure signal from the pressure sensor may be sent to sensing or notification circuitry. In response to receiving the pressure signal, the sensing or notification circuitry may create a visual or audible notification representing a flow characteristic of the fluid flow, such as a presence of, absence of, change in, or degree of fluid flow. The sensing or notification circuitry may include alarms, visual indicators (e.g., light emitting diodes (LEDs)), or the like. A variety of pressure sensors may be used including, but not limited to, pressure transducers, accelerometers, and the like. 

[0065] Fluid flow sensor 16 may be selected for a variety of flow conditions including, but not limited to, flow rate, pressure drop across fluid flow sensor 16, and the like. In some examples, fluid flow sensor 16 may be configured to produce vibrations at a flow rate between about 1 milliliter per second and about 10 milliliters per second. Fluid flow sensor 16 may be selected to produce vibrations having a variety of 

