A dry powder inhaler may include a powder storage region, an inlet channel, a dispersion chamber, and an outlet channel. A gear in a gear mechanism of the actuator is made of a resin having self-lubricating properties. A driving transistor couples the data bus to a power supply voltage in order to supply a sense current in the data read operation. The optical sensing system is positioned with respect to the sensor fixation device to sense movement corresponding to an arterial pulse when the sensor fixation device is placed against the anatomical location of the subject. The voltage applied to the voltage-controlled current sink defines the low output voltage. The mechanisms calculate, for each event group, an estimated event rate based on the sequence values of the sampled events associated with the event group and the total number of events in the sequence of events.