Macroscale and multi-functional flexible sensor networks have been widely proposed for the Internet of Things (IoT) and the trillion sensor networks. In this report, our recent progress of flexible sensors fabricated by some printing methods on user-defined non-planer substrates is presented. Especially, flexible strain sensor and temperature sensors are discussed to monitor human condition as a health monitoring device and to detect an object for a robotic prosthesis skin. In addition, flexible digital and analog circuits for the future fully integrated flexible device system are introduced.