Vibration energy harvesting is a promising solution for powering battery-free IoT systems; however, the instability of ambient vibrations presents significant challenges, such as limited harvested energy, intermittent power supply, and poor adaptability to various applications. To address these challenges, this paper proposes ViPSN2.0, a modular and reconfigurable IoT platform that supports multiple vibration energy harvesters (piezoelectric, electromagnetic, and triboelectric) and accommodates sensing tasks with varying application requirements through standardized hot-swappable interfaces. ViPSN 2.0 incorporates an energyindication power management framework tailored to various application demands, including light-duty discrete sampling, heavyduty high-power sensing, and complex-duty streaming tasks, thereby effectively managing fluctuating energy availability. The platform’s versatility and robustness are validated through three representative applications: ViPSN-Beacon, using an ultra-lowcost structural PZT (ϕ35 mm, <0.002 $) to enable a BLE advertisement from a single transient fingertip press with 100 m line of sight; ViPSN-LoRa, supporting wireless communication powered by wave vibrations in actual marine environments (Bohai Bay) with per-uplink task energy compatible with kilometer-scale field links; and ViPSN-Cam, enabling intermittent image capture and wireless transfer, delivering one frame approximately every 15 s under typical conditions. Experimental results demonstrate that ViPSN 2.0 can reliably meet a wide range of requirements in practical battery-free IoT deployments under energy-constrained conditions.

Human-motion energy harvesting is emerging as a promising solution for wearable electronics and devices, offering a sustainable power source that extends operational longevity and enhances durability. However, current techniques and prototypes have yet to achieve fully interactive, battery-free functionality. This paper presents a battery-free interactive gaming system powered by energy harvested from transient fingertip motion. To ensure the reactivity, interactivity, and stability of the fingertip motion harvester (FMH), we employ a multistable structure. The FMH unit provides a reliable energy solution by utilizing precharged potential energy within dynamically varying potential wells. Additionally, the integration of a bistable screen design facilitates seamless gaming experiences, decouples game logic from user interface mechanics, and ensures rapid system recovery after power interruptions. Beyond advancing fundamental research, this work pioneers a practical battery-free interaction paradigm based on fingertip motion, with potential for broader battery-free user interfaces and low-power interactive systems.

Touch sensing is a prominent pillar technique in various human-computer interactive scenarios, especially when touchscreen-based capacitive touch sensing has become a representative in user-end electronics. An intelligent touch-sensing system captures the capacitive touch-sensing images to recognize the objects via machine learning techniques. However, collecting the training dataset is usually laborious and time-consuming, requiring specific coding skills and knowledge. In this article, we introduced vCapTouch, a data generation method to synthesize the touch sensing data, which can be directly employed to train a machine learning model and recognize the real touching behavior, significantly lowering the need for real dataset collection. The presented method is primarily based on the idea of the digital twin. We implemented the method with Unity3D, a game engine that enables high interactivity, is easy to use, and has a low cost. We evaluated the proposed method on eight users with different touch screen devices and proved the feasibility of synthesizing the touch sensing data.

The rise of the Internet of Things (IoT) has given birth to transformative and massively deployed computing applications that raise the significant issue of energy sources. It is impractical and irresponsible to rely on wires and batteries to power trillion-level devices. One promising prediction is that energy harvesting technologies will serve as alternative power sources for IoT devices. However, we might be losing this prophecy for lack of understanding of how novice developers comprehend energy in developing IoT. In response, we conducted a mentored physical prototyping study with a two-day workshop involving eight novice developers. The study consisted of qualitative and quantitative analyses, the artifacts, interviews with both novice developers and an expert, and implications of designs for future tools. The findings reveal informational gaps that demand educational efforts and assistive features to facilitate novice developers. We present major findings from the study and implications for the design of future tools.

This demonstration showcases a battery-free wireless keyboard that utilizes the kinetic energy generated from key presses to generate electrical power. Each key incorporates a Quasi-Static Toggling harvester, which employs potential energy pre-charging to ensure a consistently reliable energy output. Extensive practical testing has confirmed that this keyboard exhibits responsiveness and low latency comparable to traditional wireless keyboards. This study represents a significant improvement over previous battery-free IoT applications that often compromised service quality, as it offers a stable energy-harvesting mechanism and provides a dependable framework for designing battery-free devices.

Summary This paper presented two schemes of parallel 2D discrete wavelet transform (DWT) on Compute Unified Device Architecture graphics processing units. For the first scheme, the image and filter are transformed to spectral domain by using Fast Fourier Transformation (FFT), multiplied and then transformed back to space domain by using inverse FFT. For the second scheme, the image pixels are convolved directly with filters. Because there is no data relevance, the convolution for data points on different positions could be executed concurrently. To reduce data transfer, the boundary extension and down‐sampling are processed during data loading stage, and transposing is completed implicitly during data storage. A similar skill is adopted when parallelizing inverse 2D DWT. To further speed up the data access, the filter coefficients are stored in the constant memory. We have parallelized the 2D DWT for dozens of wavelet types and achieved a speedup factor of over 380 times compared with that of its CPU version. We applied the parallel 2D DWT in a ring artifact removal procedure; the executing speed was accelerated near 200 times compared with its CPU version. The experimental results showed that the proposed parallel 2D DWT on graphics processing units can significantly improve the performance for a wide variety of wavelet types and is promising for various applications. Copyright © 2015 John Wiley & Sons, Ltd.

One of most desired goal of digital watermark is to protect copyright, which is hard to realize without accompanying a well designed protocol according to different applications. Online system, such as digital museum, is an advanced platform to show digital works while valued data are prone to be pirated. A secure watermarking protocol is designed to protect copyright of online system in this paper. Through embedding two watermarks separately by two independent parties in a secure way, the innocent can not be framed and the culpable not be denied. This paper not focus on watermark algorithm itself but on establishing a protocol to using watermark algorithm in online system to trace pirate.