Development of tunable filters using self-folding technology

This paper seeks to demonstrate the functionality and verify the capabilities of capacitance adjustment by a self-folding device. The self-folding devices using polyvinyl chloride (PVC) shrink wrap and copper foil tapes with predefined creases were fabricated. By modifying a simple self-folding device and exposing it to a temperature between 50 to 90 degrees Celsius, the capacitor plates could be angled from 15 to 90 degrees. As a result, the capacitance changed as the inner angle decreased, from only 0.724 picofarads measured at 90 degrees, to 2.27 picofarads measured at 15 degrees. With the capacitance for each angle obtained, the next phase of development was conducted, to determine the tune-ability using a passive high pass filter. By scaling up the number of self-folding capacitors to thirty times, a cut-off frequency of 4.99 kHz at 15 degrees up to 7.25 kHz at 75 degrees was measured. As a result, this paper’s unique way of turning a self-folding device into a capacitor demonstrates great potential for development of tunable filters using capacitance adjustment and self-folding.