Brazil: 3D Printing More Affordable Sensor Technology with the Piezoelectric diaphragm

Brazilian researchers outline recent scientific findings in ‘Evaluating Temperature Influence on Low-Cost Piezoelectric Transducer Response for 3D Printing Process Monitoring,’ a paper which was also presented at the 6th International Electronic Conference on Sensors and Applications last November.

Examining an alternative to the conventional acoustic emission (AE) sensor (often used in the monitoring of SLM, LMD, and FDM 3D printing systems), the authors investigate the viability of using the piezoelectric diaphragm, along with the influence of properties like temperature. Made with lead zirconate titanate, the piezoelectric diaphragm offers conductive qualities that create an electrical voltage when exposed to pressure—serving to detect mechanical changes. These sensors can be critical in operations, and the piezoelectric diaphragm is of special interest due to greater affordability in production.

“Monitoring manufacturing processes through sensors such as acoustic emission is a widely used practice nowadays,” explain the researchers. “However, the reduced cost of piezoelectric diaphragms is captivating compared to those of traditional AE sensors.”

Tests were performed on a Graber i3 desktop 3D printer, employing a heated MK2B Dual Power PCB table with NTC 100k thermistor type temperature sensor. The piezoelectric diaphragm (measuring 20 mm diameter by 0.42 mm thickness) was fixed to the table, and a Yokogawa DL850 oscillograph was used for both collection of data and storage purposes. Raw signals were analyzed both in time and frequency, and while ultimately the researchers showed that both sensors are similar, ‘it is perceived that temperature significantly influences the signal response of the piezoelectric transducer.’

“It was noted that the selected band from 400 to 500 Hz, which had the largest overlap of the spectra, presented the smallest errors, being 16.9% at 45 °C and 25.2% at 65 °C. At the same time, when comparing the errors of this band, 400 to 500 Hz, with those of the whole spectrum, from 0 to 800 Hz, an amplitude error for this band of approximately 1.6 times smaller is obtained at a temperature of 45 °C and 1.3 times lower at 65 °C, which are much smaller than those of the other selected band. Finally, the comparison of the errors between the temperatures of 65 °C and 45 °C revealed that the behavior of the errors is similar, although the errors are smaller, as expected, due to smaller temperature differences,” concluded the researchers.

3D printing is being used more often in the manufacturing of many different types of sensors and associated electronics, from ultra-modern medical wearables to microfluidics integrated with sensors to bioinspired sensors, and more.

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