Nature-Inspired Self-Powered Sensors and Energy Harvesters

Chapter 3 presents a comprehensive review of the various biomimetic self-powered and low-powered MEMS pressure and flow sensors that take inspiration from the biological flow sensors found in the marine world. The sensing performance of the biological flow sensors in marine animals has inspired engineers and scientists to develop efficient state-of-the-art sensors for a variety of real-life applications. In an attempt to achieve high-performance artificial flow sensors, researchers have mimicked the morphology, sensing principle, materials, and functionality of the biological sensors. Inspiration was derived from the survival hydrodynamics featured by various marine animals to develop sensors for sensing tasks in underwater vehicles. The mechanoreceptors of crocodiles have inspired the development of slowly and rapidly adapting MEMS sensory domes for passive underwater sensing. Likewise, the lateral line sensing system in fishes which is capable of generating a three-dimensional map of the surroundings was mimicked to achieve artificial hydrodynamic vision on underwater vehicles. Harbor seals are known to achieve high sensitivity in sensing flows within the wake street of a swimming fish due to the undulatory geometry of the whiskers. Whisker inspired structures were embedded into MEMS sensing membranes to understand their vortex shedding behavior. At the outset, this work comprehensively reviews the sensing mechanisms observed in fishes, crocodiles, and harbor seals. In addition, this chapter presents an in-depth commentary on the recent developments in this area where different researchers have taken inspiration from these aforementioned underwater creatures and developed some of the most efficient artificial sensing systems

Single and bundled carbon nanofibers as ultralightweight and flexible piezoresistive sensors

This work demonstrates the application of electrospun single and bundled carbon nanofibers (CNFs) as piezoresistive sensing elements in flexible and ultralightweight sensors. Material, electrical, and nanomechanical characterizations were conducted on the CNFs to understand the effect of the critical synthesis parameter—the pyrolyzation temperature on the morphological, structural, and electrical properties. The mechanism of conductive path change under the influence of external stress was hypothesized to explain the piezoresistive behavior observed in the CNF bundles. Quasi-static tensile strain characterization of the CNF bundle-based flexible strain sensor showed a linear response with an average gauge factor of 11.14 (for tensile strains up to 50%). Furthermore, conductive graphitic domain discontinuity model was invoked to explain the piezoresistivity originating in a single isolated electrospun CNF. Finally, a single piezoresistive CNF was utilized as a sensing element in an NEMS flow sensor to demonstrate air flow sensing in the range of 5–35 m/s

Broadband Loop Antenna on Soft Contact Lens for Wireless Ocular Physiological Monitoring

This paper presents a novel loop antenna with broadband for wireless ocular physiological monitoring (WOPM). The antenna is fabricated on a thin-film poly-para-xylylene C (parylene C) substrate with a small thickness of 11 μm and dimension of π×6.5×6.5 mm2. With the advantage of small size, the proposed antenna is suitable to apply to the soft contact lens and transmit the signal in microelectromechanical Systems (MEMS). Because the pig's eye and human's eye have similar parameters of conductivity and permittivity, the experimental results are obtained by applying the proposed antenna on the pig's eye and cover from 1.54 to 6 GHz for ISM band (2.4 and 5.8 GHz) applications. The measured antenna radiation patterns, antenna gains, and radiation efficiency will be demonstrated in this paper, which are suitable for application of wireless ocular physiological monitoring

Localization Algorithms of Underwater Wireless Sensor Networks: A Survey

In Underwater Wireless Sensor Networks (UWSNs), localization is one of most important technologies since it plays a critical role in many applications. Motivated by widespread adoption of localization, in this paper, we present a comprehensive survey of localization algorithms. First, we classify localization algorithms into three categories based on sensor nodes’ mobility: stationary localization algorithms, mobile localization algorithms and hybrid localization algorithms. Moreover, we compare the localization algorithms in detail and analyze future research directions of localization algorithms in UWSNs

PZT-Based Piezoelectrically Driven Microlens Actuator For Potential Application In Micro-Optics

This dissertation reports the development of a MEMS PZT-based piezoelectrically driven microlens actuator for potential use in micro-optics applications. The actuator consists of six uniquely arranged piezoelectric beams configured in d31 mode. One end of the beam is fixed to the substrate and the other end connected to a serpentine spring supporting a microlens holding platform. The microlens actuator exhibits large out-of-plane displacement of 145 um at 100kV/cm (22V) with a high resonance frequency of 1.96 kHz when it is free from a microlens loading, and 0.673 kHz with a 330 ug PDMS lens loading. The parameters governing the design and fabrication conditions to obtain an optimum actuation performance are discussed in detail. As part of the microlens actuator development, a series of original studies have been conducted. These include: (i) The study of Ultra-High Vacuum E-beam Evaporated Polysilicon (UHVEEPoly) thin-film for forming Lead Zirconate Titanate (PZT) based piezoelectric MEMS. The film is used as a passive structural layer in a unimorph PZT micro-cantilever actuator to demonstrate its suitability as an alternative platform for forming PZT based devices. In particular, this technique enables a cost-effective process and versatility of forming MEMS structures compared to conventional platforms. (ii) The development of PZT bimorph actuator with polysilicon as the passive structural layer. This novel arrangement has been made possible due to the low stress and low thermal budget properties of the UHVEEPoly film which can be formed without influencing the quality of the piezoelectric layer deposited prior. This configuration has unique suitability for the micro-actuation mechanism presented in this work that enables the possibility of bi-directional actuation and reduction in device footprint area. (iii) A novel approach to enhance the out-of-plane uni-directional actuation without compromising resonance frequency or changing the overall actuator design has been demonstrated. The study exploits the use of the UHVEEPoly and RF-sputtered SiO2 films as the passive structural layer to manipulate the residual moment created from the residual stress in the multi-layered thin-film structure. By residual stress manipulation of the passive layer, an enhancement of more than 36% in the displacement range has been obtained from the microlens actuator; (iv) The proposed microlens actuator has demonstrated the capability to function as an optical focusing mechanism by changing the focus of a laser pointer with actuation; (v) Studies on the development to implement an integration of on-chip piezoresistive sensor with the microlens actuator has been discussed

A comparative analysis on artificial neural network-based two-stage clustering

The artificial neural network (ANN), which is capable of noise removal and data complexity reduction, has been regarded as one of outstanding intermediaries in the two-stage clustering procedures. Various ANN-based two-stage clustering procedures have been individually proposed; however, the performance among those methods has not been examined yet. In this study, a preliminary comparative analysis is conducted in four benchmark data-sets and a real-world market data-set, which are used to simulate various conditions for evaluation purposes. The experiment results suggest that high-accuracy self-organizing feature map can potentially improve the effectiveness of decision-making

"The screen shows movement - movement is interesting!" exploring effects of multimedia stories on preschool children's story comprehension and enjoyment

Purpose Using multimedia and print storybooks, the purpose of this paper is to compare preschool children’s reading engagement with and without adult support. Design/methodology/approach A within-subject design is used to explore the effects of multimedia stories in supporting preschool children’s story comprehension and reading enjoyment. A total of 24 children aged five to six years old from a local preschool in Taiwan participated in the experiments. Findings A statistical analysis revealed the (non)differences in story comprehension between multimedia and print storybooks, with and without adult support. A content analysis revealed several important themes affecting children’s reading enjoyment. These included multimedia elements (particularly motion and sound effects), haptic perception and the pause function. Research limitations/implications Native Chinese speaking children participated in one-to-one sessions in Taiwan. To ascertain the generalizability of the findings presented in this study, further research is encouraged in other cultural contexts and settings. Practical implications The paper provides insights into how multimedia and interactive features affect and enhance children’s enjoyment. Recommendations are made to assist library professionals to incorporate digital media into children’s programs. Originality/value Children’s reading motivation and engagement are often linked with improved reading attainments. This study elicited a range of perspectives and themes relating to what the children themselves felt influenced their enjoyment when reading print or multimedia storybooks. Findings were analyzed in a theoretical framework of facets of engagement