Technological progress in integrated, low-power, CMOS communication devices and sensors makes a rich design space of networked sensors viable. They can be deeply embedded in the physical world and spread throughout our environment like smart dust. The missing elements are an overall system architecture and a methodology for systematic advance. To this end, we identify key requirements, develop a small device that is representative of the class, design a tiny event-driven operating system, and show that it provides support for efficient modularity and concurrency-intensive operation. Our operating system fits in 178 bytes of memory, propagates events in the time it takes to copy 1.25 bytes of memory, context switches in the time it takes to copy 6 bytes of memory and supports two level scheduling. The analysis lays a groundwork for future architectural advances.

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System architecture directions for networked sensors

The term ‘‘Internet-of-Things’’ is used as an umbrella keyword for covering various aspects related to the extension of the Internet and the Web into the physical realm, by means of the widespread deployment of spatially distributed devices with embedded identification, sensing and/or actuation capabilities. Internet-of-Things envisions a future in which digital and physical entities can be linked, by means of appropriate information and communication technologies, to enable a whole new class of applications and services. In this article, we present a survey of technologies, applications and research challenges for Internetof-Things.

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Internet of things: Vision, applications and research challenges

This paper reviews the state-of-the art in vibration energy harvesting for wireless, self-powered microsystems. Vibration-powered generators are typically, although not exclusively, inertial spring and mass systems. The characteristic equations for inertial-based generators are presented, along with the specific damping equations that relate to the three main transduction mechanisms employed to extract energy from the system. These transduction mechanisms are: piezoelectric, electromagnetic and electrostatic. Piezoelectric generators employ active materials that generate a charge when mechanically stressed. A comprehensive review of existing piezoelectric generators is presented, including impact coupled, resonant and human-based devices. Electromagnetic generators employ electromagnetic induction arising from the relative motion between a magnetic flux gradient and a conductor. Electromagnetic generators presented in the literature are reviewed including large scale discrete devices and wafer-scale integrated versions. Electrostatic generators utilize the relative movement between electrically isolated charged capacitor plates to generate energy. The work done against the electrostatic force between the plates provides the harvested energy. Electrostatic-based generators are reviewed under the classifications of in-plane overlap varying, in-plane gap closing and out-of-plane gap closing; the Coulomb force parametric generator and electret-based generators are also covered. The coupling factor of each transduction mechanism is discussed and all the devices presented in the literature are summarized in tables classified by transduction type; conclusions are drawn as to the suitability of the various techniques.

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Energy harvesting vibration sources for microsystems applications

A wireless network consisting of a large number of small sensors with low-power transceivers can be an effective tool for gathering data in a variety of environments. The data collected by each sensor is communicated through the network to a single processing center that uses all reported data to determine characteristics of the environment or detect an event. The communication or message passing process must be designed to conserve the limited energy resources of the sensors. Clustering sensors into groups, so that sensors communicate information only to clusterheads and then the clusterheads communicate the aggregated information to the processing center, may save energy. In this paper, we propose a distributed, randomized clustering algorithm to organize the sensors in a wireless sensor network into clusters. We then extend this algorithm to generate a hierarchy of clusterheads and observe that the energy savings increase with the number of levels in the hierarchy. Results in stochastic geometry are used to derive solutions for the values of parameters of our algorithm that minimize the total energy spent in the network when all sensors report data through the clusterheads to the processing center.

/pdf/an-energy-efficient-hierarchical-clustering-algorithm-for-574o6gyna1.pdf

An energy efficient hierarchical clustering algorithm for wireless sensor networks

Enabling technologies for wireless sensor networks have gained considerable attention in research communities over the past few years. It is highly desirable, even necessary in certain situations, for wireless sensor nodes to be self-powered. With this goal in mind, a vibration based piezoelectric generator has been developed as an enabling technology for wireless sensor networks. The focus of this paper is to discuss the modeling, design, and optimization of a piezoelectric generator based on a two-layer bending element. An analytical model of the generator has been developed and validated. In addition to providing intuitive design insight, the model has been used as the basis for design optimization. Designs of 1 cm3 in size generated using the model have demonstrated a power output of 375 µW from a vibration source of 2.5 m s−2 at 120 Hz. Furthermore, a 1 cm3 generator has been used to power a custom designed 1.9 GHz radio transmitter from the same vibration source.

https://iopscience.iop.org/article/10.1088/0964-1726/13/5/018/pdf

A piezoelectric vibration based generator for wireless electronics

Smart Dust: Communicating with a Cubic-Millimeter Computer

A 16 mm/sup 3/ autonomous solar-powered sensor node with bidirectional optical communication for distributed sensor networks has been demonstrated. The device digitizes integrated sensor signals and transmits/receives data over a free-space optical link. The system consists of three die - a 0.25 /spl mu/m CMOS ASIC, a 2.6 mm/sup 2/ SOI solar cell array, and a micromachined four-quadrant corner-cube retroreflector (CCR), allowing it to be used in a one-to-many network configuration. The CMOS ASIC includes a photosensor integrated 3 MHz oscillator, 69 pJ/bit optical receiver and 31 pJ/sample ADC.

/pdf/an-autonomous-16-mm-sup-3-solar-powered-node-for-distributed-4xv603f9n0.pdf

An autonomous 16 mm/sup 3/ solar-powered node for distributed wireless sensor networks

A 12pJ/instruction microcontroller with embedded SPAM designed specifically for use in mm/sup 3/ wireless sensor nodes is described. It features highly independent subsystems for sensor sampling, transmission, and receiving that maximize the datapath sleep time as well as 100nW integrated oscillators with rapid power-cycling. Designed in 0.25/spl mu/m technology, the 0.38mm/sup 2/ core consumes 5.9/spl mu/W from a 1V supply when running at 500kHz.

An ultra-low energy microcontroller for Smart Dust wireless sensor networks

MEMS technology is enabling the development of inexpensive, autonomous wireless sensor nodes with volumes ranging from cubic mm to several cubic cm. These tiny sensor nodes can form rapidly deployed, massive distributed networks to allow unobtrusive, spatially dense, sensing and communication. MEMS enable these devices by reducing both the volume and energy consumption of various components. This paper reviews some of the wireless sensor nodes under development and applicable MEMS devices for small and efficient optical communication, micropower generation, and sensing. In addition, CMOS post-process micromachining is discussed as a method of achieving low cost and high integration.

/pdf/mems-for-distributed-wireless-sensor-networks-1dw10s9uwx.pdf

MEMS for distributed wireless sensor networks

We have demonstrated a 138 mm/sup 3/ autonomous uni-directional sensing/communication mote that optically transmits a measure of the ambient light level. We have also developed a 63 mm/sup 3/ autonomous bi-directional communication mote that receives an optical signal, generates a pseudorandom sequence based on this signal to emulate sensor data, then optically transmits the result, although it has only been demonstrated in a bench configuration at this time. The latter system contains a micromachined corner cube reflector, a 0.078 mm/sup 3/ CMOS chip that consumes 75 /spl mu/W, and a Mn-Ti-Li cell, but we have also demonstrated operation from an /spl sim/2 mm/sup 2/ solar cell. These motes allow us to demonstrate necessary concepts of Smart Dust such as optical data transmission, data processing, energy management, miniaturization, and system integration.

/pdf/smart-dust-mote-forerunners-vehfdpw5m5.pdf

B. Warneke

Papers

Smart Dust: Communicating with a Cubic-Millimeter Computer

An autonomous 16 mm/sup 3/ solar-powered node for distributed wireless sensor networks

An ultra-low energy microcontroller for Smart Dust wireless sensor networks

MEMS for distributed wireless sensor networks

Smart dust mote forerunners