Capacitive Touch Panel with Low Sensitivity to Water Drop employing Mutual-coupling Electrical Field Shaping Technique

This paper proposes a novel method to reduce the water interference on the touch panel based on mutual-capacitance sensing in human finger detection. As the height of a finger (height >10 mm) is far larger than that of a water-drop (height 10 mm) and low in the low-height space (height <1 mm), the sensing cell can be designed to distinguish the finger from the water-drop. To achieve this density distribution of the electrical field, the mutual-coupling electrical field shaping (MEFS) technique is employed to build the sensing cell. The drawback of the MEFS sensing cell is large parasitic capacitance, which can be overcome by a readout IC with low sensitivity to parasitic capacitance. Experiments show that the output of the IC with the MEFS sensing cell is 1.11 V when the sensing cell is touched by the water-drop and 1.23 V when the sensing cell is touched by the finger, respectively. In contrast, the output of the IC with the traditional sensing cell is 1.32 and 1.33 V when the sensing cell is touched by the water-drop and the finger, respectively. This demonstrates that the MEFS sensing cell can better distinguish the finger from the water-drop than the traditional sensing cell does.National Research Foundation (NRF)Accepted versionThis work was supported in part by the National Natural Science Foundation of China (NSFC) under Grant 61771363, in part by the China Scholarship Council (CSC) under Grant 201706960042, and in part by the National Research Foundation of Singapore under Grant NRF-CRP11-2012-01

Innovation of traditional series of combination process for alumina production

When the Bayer process is applied to the middle/low grade bauxite with A/S <5, the production flow is simple and energy consumption is low, but the yield rate and resource availability are low as well. However if a series of combination process is used a high yield rate can be high, but the energy consumption is also high and Bayer process system is affected. In this paper an innovative series combination process to minimize the energy consumption, and to reduce the negative effects caused to Bayer process system is proposed for optimal production of alumina from middle/low grade bauxite with SiO2 mainly existing in the form of kaolinite

Controllably enhancing stretchability of highly sensitive fiber-based strain sensors for intelligent monitoring

Functional strain sensing is essential to develop health monitoring and Internet of Things. The performance of either narrow sensing range or low sensitivity restricts strain sensors in a wider range of future applications. Attaining both high sensitivity and wide sensing range of a strain sensor remains challenging. Herein, a cluster-type microstructures strategy is proposed for engineering high stretchability of highly sensitive strain sensor. The resistance change of the strain sensor is determined by the deformation of the cluster-type microstructures from close arrangement to orderly interval state during being stretched. Because of the unique geometric structure and conductive connection type of the sensing material, the strain sensor achieves a considerable performance that features both high sensitivity (gauge factor up to 2700) and high stretchability (sensing range of 160% strain). Fast response time and long-term stability are other characteristics of the strain sensor. Monitoring of multiple limb joints and controlling of audible and visual devices are demonstrated as the proof-of-concept abilities of the strain sensor. This study not only puts forward a novel design thought of strain sensor but also offers considerable insights into its potential value toward burgeoning fields including but not limited to real-time health monitoring and intelligent controls.National Research Foundation (NRF)Accepted versionThis work was supported by the National Research Foundation of Singapore (No. NRF-CRP11-2012-01)

Image reconstruction of immersed ultrasonic testing for strongly attenuative materials

With the development of industrial materials, the objects of ultrasonic non-destructive evaluation (UNDE) have been expanded from metals to composite and polymer materials. However, composite and polymer materials are elastoplastic. The elastoplastic induced strong acoustic attenuation and dispersion affect the phases and waveforms of ultrasound waves. If overlooking these effects, the ultrasound reconstruction image will generate position deviation, resolution degradation and detail loss. To overcome this kind of deficiency, this paper introduces an ultrasound reconstruction that takes account of attenuation and dispersion compensation for the UNDE applications. It is derived from phase shift migration (PSM) by modifying the phase shift term with compensations of the attenuation and dispersion. This method can resolve imaging of layered media with depth-variant attenuation, such as commonly used immersed ultrasonic testing cases, while inheriting the high computational efficiency of PSM. Based on simulation and experimental results, the proposed method corrects the reconstruction deviation, improves image resolution, and restore details caused by depth variant attenuation and dispersion which literature methods cannot. For reconstructing a 3D image data sized of 4000 × 140 × 300 pixels, the memory cost can be controlled under 300 MB using recursive implementation, and the time cost can be reduced to 0.4 s using parallelization implementation

Synergistic sensing of stratified structures enhancing touch recognition for multifunctional interactive electronics

Efficient touch feedback, capable of monitoring the magnitude of force and identifying active location, is significant to artificial intelligence and interactive robotics. It generally needs the integration of multitudinous sensing elements and intricate manufacturing procedures. Here we propose a multifunctional paper-based touch sensor to realize touch trajectory recognition as well as achieve pressure information. The asymmetric and symmetric structures are designed to skillfully construct localization layer and pressure sensing layer. These functional layers effectively assemble a scalable touch sensor and, thus, greatly simplify the device's architecture with the competitive advantages of easiness in fabrication, cost-effectiveness, self-switching characteristic, and programmability in interactive function. Through coding and using the electrical signals, human-computer interaction, human-machine interaction, and force-enhanced cryptographic matrix are explored and demonstrate the feasibility of the proposed touch sensor. This work provides a novel mechanosensational sensing paradigm to leverage the complex physics of a feasible strategy for advancing human-related interactive electronics.National Research Foundation (NRF)Accepted versionThis work was supported by the National Research Foundation of Singapore (No. NRF-CRP11-2012-01). The authors declare that they have no competing interests

Flexible, Cuttable, and Self-Waterproof Bending Strain Sensors Using Microcracked Gold Nanofilms@Paper Substrate

Rapid advances in functional sensing electronics place tremendous demands on innovation toward creative uses of versatile advanced materials and effective designs of device structures. Here, we first report a feasible and effective fabrication strategy to integrate commercial abrasive papers with microcracked gold (Au) nanofilms to construct cuttable and self-waterproof crack-based resistive bending strain sensors. Via introducing surface microstructures, the sensitivities of the bending strain sensors are greatly enhanced by 27 times than that of the sensors without surface microstructures, putting forward an alternative suggestion for other flexible electronics to improve their performances. Besides, the bending strain sensors also endow rapid response and relaxation time of 20 ms and ultrahigh stability of >18 000 strain loading–unloading cycles in conjunction with flexibility and robustness. In addition, the concepts of cuttability and self-waterproofness (attain and even surpass IPX-7) of the bending strain sensors have been demonstrated. Because of the distinctive sensing properties, flexibility, cuttability, and self-waterproofness, the bending strain sensors are attractive and promising for wearable electronic devices and smart health monitoring system

Hierarchically distributed microstructure design of haptic sensors for personalized fingertip mechanosensational manipulation

Strategies to help reconstruct and restore haptic perception are essential for control of prosthetic limbs, clinical rehabilitation evaluation, and robotic manipulation. Here, we propose a hierarchically distributed microstructure based on electric contact theory to develop haptic sensors. The sensing range of the haptic sensor based on a hierarchically distributed microstructure is greatly enhanced by ten times relative to the one of the haptic sensor based on a common structure. Furthermore, variation in the response signal of the haptic sensor is up to five orders of magnitude and scales with the external pressure between 0.5 and 100 kPa, which is close to the range that a finger normally feels. Personalized manipulation of electrical appliances, a three-dimensional password matrix, and gesture control of a data glove demonstrate the fascinating potential of the haptic sensors for human–machine interactive systems, force-enhanced security systems, and wearable electrical systems.NRF (Natl Research Foundation, S’pore)Accepted versio

Directly printed wearable electronic sensing textiles towards human – machine interfaces

Gesture control is an emerging technological goal in the field of human–machine interfaces (HMIs). Optical fibers or metal strain sensors as sensing elements are generally complex and not sensitive enough to accurately capture gestures, and thus there is a need for additional complicated signal optimization. Electronic sensing textiles hold great promise for the next generation of wearable electronics. Here, soft, deformable and ultrahigh-performance textile strain sensors are fabricated by directly stencil printing silver ink on pre-stretched textiles towards HMIs. These textile strain sensors exhibit ultrahigh sensitivity (a gauge factor of ∼2000), stretchability (up to 60% strain), and durability (>10 000 stretching cycles). Through a simple auxiliary signal processing circuit with Bluetooth communication technology, an intelligent glove assembled with these textile strain sensors is prepared, which is capable of detecting the full range of fingers’ bending and can translate the fingers’ bending into wireless control commands. Immediate applications, for example, as a smart car director, for wireless typing, and as a remote PowerPoint controller, bring out the great practical value of these textile strain sensors in the field of wearable electronics. This work provides a new prospective for achieving wearable sensing electronic textiles with ultrahigh performance towards HMIs, and will further expand their impact in the field of the Internet of Things.NRF (Natl Research Foundation, S’pore)Accepted versio

3D viscoplastic finite element modeling of dislocation generation in a large size Si ingot of the directional solidification stage

Growing very large size silicon ingots with low dislocation density is a critical issue for the photovoltaic industry to reduce the production cost of the high-efficiency solar cell for affordable green energy. The thermal stresses, which are produced as the result of the non-uniform temperature field, would generate dislocation in the ingot. This is a complicated thermal viscoplasticity process during the cooling process of crystal growth. A nonlinear three-dimensional transient formulation derived from the Hassen-Sumino model (HAS) was applied to predict the number of dislocation densities, which couples the macroscopic viscoplastic deformation with the microscopic dislocation dynamics. A typical cooling process during the growth of very large size (G5 size: 0.84 m × 0.84 m × 0.3 m) Si ingot is used as an example to validate the developed HAS model and the results are compared with those obtained from qualitatively critical resolved shear stress model (CRSS). The result demonstrates that this finite element model not only predicts a similar pattern of dislocation generation with the CRSS model but also anticipate the dislocation density quantity generated in the Si ingot. A modified cooling process is also employed to study the effect of the cooling process on the generation of the dislocation. It clearly shows that dislocation density is drastically decreased by modifying the cooling process. The results obtained from this model can provide valuable information for engineers to design a better cooling process for reducing the dislocation density produced in the Si ingot under the crystal growth process.Published versio