A demonstration of power enhancement by nonlinear oscillation in a millimeter-sized electrostatic vibrational energy harvester for the future Internet of Things is presented. To enable nonlinearity in microelectromechanical system (MEMS) devices, we selected a gold spring as a component of the MEMS structure for its lower Young's modulus than conventional materials, a ductile characteristic, and an electrical conductivity. The mechanical characteristics of the fabricated MEMS device related to the nonlinear phenomenon were examined. The charging characteristics of an ethylene tetrafluoroethylene copolymer (ETFE) electret film for electrostatic induction were also evaluated. Nonlinear oscillation for the millimeter-sized energy harvester with the ETFE electret was confirmed experimentally by applying external vibration. The oscillation resulted in a bandwidth two times broader than that by linear oscillation. The normalized harvester effectiveness of the nonlinear oscillation was 5.1 times higher than that of the linear one.

A system which employs a stylus as an input device is suitable for creative activities like writing and painting. However, such a system does not always provide the user with a GUI that is easy to operate using the stylus. In addition, system usability is diminished because the stylus is not always integrated into the system in a way that takes into consideration the features of a pen. The purpose of our research is to improve the usability of a system which uses a stylus as an input device. We propose shortcut actions, which are interaction techniques for operation with a stylus that are controlled through a user's hand motions made in the air. We developed the Context Sensitive Stylus as a device to implement the shortcut actions. The Context Sensitive Stylus consists of an accelerometer and a conventional stylus. We also developed application programs to which we applied the shortcut actions; e.g., a drawing tool, a scroll supporting tool, and so on. Results from our evaluation of the shortcut actions indicate that users can concentrate better on their work when using the shortcut actions than when using conventional menu operations.