This paper studies short-pulse on-off keying (OOK) for microfluidic molecular communication with Langmuir adsorption-based biosensor receivers. We develop a compact symbol-rate model that captures receptor-memory-induced inter-symbol interference (ISI), binomial pulse-end observations, and decision-feedback midpoint-threshold detection. Preliminary simulations show that longer symbol intervals mitigate ISI, while longer short pulses improve bit-0/bit-1 separation.