Researchers have developed a soft, flexible film that can sense the presence of nearby objects without physically touching them. This noncontact sensor technology is being used to detect eyelash proximity in blink-tracking glasses. Noncontact sensors can identify or measure an object without direct contact, and examples include infrared thermometers and vehicle proximity notification systems. One type of noncontact sensor relies on static electricity to detect closeness and small motions, which has the potential to enhance smart devices by allowing phone screens to recognize more finger gestures. However, these sensors have been limited in terms of what types of objects they can detect, how long they hold a charge, and how difficult they are to fabricate.
The researchers fabricated a three-part system for the sensor, using fluorinated ethylene propylene (FEP) for the top sensing layer, an electrically conductive film for the middle layer, and a flexible plastic base for the bottom layer. FEP is an electret material that is electrically charged and produces an external electrostatic field, similar to a magnet producing a magnetic field. The sensor was then electrically charged and tested to detect objects approaching the surface without physical contact. The sensor was able to detect objects made of glass, rubber, aluminum, and paper that were nearly touching it but not quite, from 2 to 20 millimeters away. The sensor held its charge for over 3,000 different approach-withdraw cycles over almost two hours.
In a demonstration of the new sensing film, the researchers attached it to the inner side of eyeglass lenses. When worn by a person, the glasses were able to detect the approach of eyelashes and identify when the wearer blinked, using Morse code for “E C U S T,” which is the abbreviation for the researchers’ institution. The researchers suggest that in the future, these noncontact sensors could be used to help people who are unable to speak or use sign language communicate, or even to detect drowsiness while driving. The study was supported by funding from various organizations including the Natural Science Foundation of China and the National Key Research and Development Program of China.
Overall, the development of noncontact sensors that can detect objects without physical contact has the potential to improve smart devices and assist individuals with communication difficulties. By using static electricity to sense objects in close proximity, researchers have created a flexible sensor that is clear and able to detect a variety of materials approaching it from a short distance. The ability of this sensor to detect objects without making physical contact opens up opportunities for a wide range of applications, including gesture recognition on smart devices and safety enhancements for drivers. The demonstrated use of the sensor in blink-tracking glasses shows the potential for this technology to aid those who are nonverbal or have communication challenges, highlighting the importance of further research and development in this area.