quasi-static E-fields have rarely been utilized in visualization or communication tools. Sharks and stingrays are some of the unique creatures that can feel quasistatic E-fields when searching for their prey. [4] Detecting the imperceptible quasistatic E-fields has the potential to open a new method of visualization. [5] For example, monitoring static electricity can avoid electrostatic discharge, which causes the breakdown of electronic devices [6] and fire accidents. [7] Proximity sensing based on the E-field is useful in robotics and human-machine interfaces. [8] A combination of E-field sensors and electrets, which have a quasi-permanent charge or dipole polarization, can be used to develop a new human-machine interface, such as touchscreen devices. The difficulty in visualizing quasi-static E-fields is mainly due to low-energy photons and the lack of integrable devices with high sensitivity to detect them. Furthermore, while there are lenses capable of perceiving different wavelengths of electromagnetic radiation, no such technology exists to see quasi-static E-fields. Conventional methods for measuring quasi-static E-fields or charges include gold-leaf electroscopes, [9] Faraday cages, and surface potential sensors. [10] A typical surface potential sensor uses metal mechanical choppers to modulate the electric flux and precisely measure the E-field. However, these systems are not suitable for application in 2D imaging because of their size (>1 cm 3 ), weight (>10 g), and cost (>$100) for each pixel.In recent studies, it has been shown that E-field sensing using organic semiconductors are realizable. Wang et al. used an organic semiconductor, a single rubrene crystal with two gold electrodes that was not a transistor, to detect the proximity of an atomic force microscope tip, a human finger, and a plastic ruler, each at a distance of several millimeters. [11] Liu et al. used a thin-film organic semiconductor polymer; poly[2,5-(2-octyl dodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno[3,2-b]thiophene)], as a field-effect transistor with a silver wire connected to the gate electrode, and demonstrated proximity sensing up to a distance of several centimeters. [12] Furthermore, Lv et al. used a dinaphtho[2, thiophene organic semiconductor film with two gold electrodes (not a transistor) deposited in a vacuum to sense the proximity of charged objects. [13] The same study also demonstrated a sensor array on an ultra-flexible substrate. These sensors utilize the so-called field effect, [14] where charge carriers are induced in the organic semiconductor layers by the E-field. Although these studies have successfully detected the proximity of various charged objects, the sensitivity of the sensors is not sufficiently Unlike electromagnetic radiation such as radio waves, infrared-visibleultraviolet, and X-rays, static or quasi-static electric fields are rarely utilized for visualization in people's lives and industries. The difficulty in measuring quasi-static electric fields is mainly due to lo...
