Recently, flexible pressure sensors featuring enhanced sensitivity and durability through nano/micro additive manufacturing have been employed in various fields, including medical monitoring, E-skin technology, and soft robotics. This study focuses on the fabrication and verification of an interdigitated electrode (IDE) based flexible pressure sensor that incorporates microstructures, utilizing a direct patterning-based additive process. The IDE-patterned sample was designed with a total size of 7.95 × 10 mm2, a line width of 150 µm, a spacing of 200 µm, and a probe pad measuring 1.25 × 2 mm2. It was fabricated using AgNP ink on a primed 100 µm thick polyethylene naphthalate (PEN) substrate. The electrode layer was subsequently covered with a sensing layer made of a MWCNT/Ecoflex composite material, resulting in the final pressure sensor sample. Measurements indicated that the sensor exhibited good sensitivity and response speed, and it was confirmed that further improvements in sensitivity could be achieved by optimizing the size, spacing, and height of the microstructures. Building on the flexible pressure sensor structure developed in this study, we plan to pursue future research aimed at fabricating array sensors with integrated circuits and exploring their applicability in wearable devices for pressure sensing and control functions.

A separator used by marine engine functions as a purifier by dividing engine oil into pure oil and impurities. By rotating the separator at a high speed between 1800 to 4500 rpm, fine particles of oil inside the separator are centrifuged due to the weight difference when the engine oil is refined. The impurities, so-called sludge, should be manually removed by taking the separator apart from the oil purifier system unless the accumulated sludge is measured and monitored in real time. A manual discharge of the sludge causes an increase of cycle time to clean the engine oil as well as operator exposure of safety risks. Therefore, the development of automatic system with a sludge monitor and an actuator is necessary for ship engine efficiency. In this paper, the pressure difference from the accumulated sludge is monitored via a pressure sensor. By measuring the pressure exerted at the wall surface, the amount of sludge was quantitatively estimated within the error of 0.032-0.091 kg when the oil purifier system has been automated.

Pressure sensors are widely used in industries, including cars and coolers. Highly accurate pressure sensors are capable of corresponding to changes in the surrounding temperature. Additionally, the manufacturing process of pressure sensors greatly impacts the cost and degree of precision. This study undertook to examine the manufacturing process of pressure sensors, especially those using ceramic diaphragm. Ruthenium oxide (RuO2) was used instead of strain gauge for piezoresistance. TC thermistor (temperature coefficient) resistance compensated for changes in outdoor air temperature. Furthermore, thick-film resistors were precisely adjusted with laser trimming technology. These processes resulted in the production of a high accuracy diaphragm pressure sensor having an ability to correspond to changes in outdoor temperatures.