Methods and apparatus for measuring changes in pressure in a fluidic system are described. In one aspect, an apparatus for measuring pressure as described herein includes a test channel (e.g., a first fluidic channel (120)) and a control channel (e.g., a second fluidic channel (125)) that join a measuring region (130) downstream of the test and control channels. In some embodiments, fluid flowing in the test and control channels can be laminar and form a stable fluid interface in the measuring region. A property of the fluid interface, such as the position of the fluid interface, e.g., relative to a width of the measuring region, may be measured, in some cases visually. In some embodiments, introduction of a component (e.g., a cell) into the test channel can cause a change in pressure drop in the test channel. This change in pressure drop can cause a deflection of the fluid interface. The amplitude of deflection of the fluid interface can be correlated with the change in pressure caused by the introduction of the component in the test channel. In some cases, changes in pressure can be associated with a characteristic (e.g., a mechanical property) of the component. Advantageously, changes in pressure can be measured dynamically and in real time.