Design of an Automated Pill Counter for Pharmacy Dispensing in Nigerian Tertiary Hospital Pharmacies

Manual pill counting in hospital pharmacy dispensing is a time-consuming and error-prone process that contributes to medication dispensing errors and pharmacist workflow inefficiency in Nigerian tertiary hospitals. This study designs an automated pill counter prototype for pharmacy dispensing applications at tertiary hospital pharmacies. The device employs a vibrating hopper feeding mechanism to singulate tablets or capsules onto a conveyor belt, with an infrared light gate sensor array counting pills as they pass through the sensor zone before dropping into a patient dose cup. An Arduino Mega microcontroller manages the vibration frequency, conveyor speed, sensor data acquisition, and count display. A preset dose selector allows the pharmacist to programme the required pill count, with the conveyor automatically stopping when the target count is reached. The system accommodates pills from 5 to 18 millimetres diameter by means of adjustable guide rails. Count accuracy testing on five tablet types of varying size, shape, and weight confirmed a counting accuracy of 99.1 percent across five thousand individually validated tablet dispensing cycles. Throughput testing demonstrated a dispensing speed of 120 to 180 tablets per minute, approximately six times faster than trained manual counting. Jamming events during testing occurred at a rate of one per two hundred cycles, addressed by a manual reset procedure. The display shows the current count and alerts the pharmacist upon dose completion. Total fabrication cost was estimated at thirty-five thousand naira. The study recommends a formal dispensing error rate comparison study at a tertiary hospital pharmacy. Keywords: automated pill counter, pharmacy dispensing, infrared sensor, medication safety, tertiary hospital.