Design of a Portable and Low-Cost Mass Sensitive Quartz Tuning Fork Sensor ^†

The resonance frequency of quartz tuning fork (QTF) depends on the mass adsorbed to its prongs, so it is used to measure minor mass changes and detect target analyte at picogram levels. Although, in several studies, QTF transducers have been implemented in sensors (mass, viscosity, humidity, temperature etc.) or biosensors, their electronic set-up has been expensive and non-portable. Moreover, explanations on details of their instrumentation have been limited and based on noncommercial products. In this study, a low-cost, portable, compact and relatively new QTF sensor device is presented. The instrument is based on a low-cost microcontroller which controls both the direct digital synthesizing (DDS) chip and data acquisition. QTF is excited by the aid of a DDS chip and its output is directly read via the same microcontroller. Moreover, six different types of QTFs with 32 kHz, 32.768 kHz, 40 kHz, 65.536 kHz, 75 kHz and 100 kHz resonance frequencies have been tested. As a case study, temperature effects on stability are studied for the most common type of QTF with the resonance frequency of 32.768 kHz. Consequently, a QTF sensor device is fabricated with more advanced features compared to its alternatives, leading to a more accurate measurement method.