Kristofer S.J. Pister (Advisor)

Research Advised by Professor Kristofer S.J. Pister

Pister Group:  List of Projects | List of Researchers

Optical MEMS for Free-Space Communication

Lixia Zhou
Kristofer S.J. Pister
Joseph M. Kahn
Roger T. Howe
Alice M. Agogino
The convergence of MEMS technology with communication and digital circuitry makes high-speed, low power, free-space communication links over distances up to several km possible. MEMS corner cube retroreflectors (CCRs) are proposed to work as a passive optical transmitter, sending collected information back to an interrogating center. MEMS scanning microm...

Piezoelectric Aluminum Nitride Vibrating RF MEMS for Radio Front-End Technology

Gianluca Piazza
Albert P. Pisano
Roger T. Howe
Liwei Lin
Kristofer S.J. Pister
The demand of consumer electronics for RF filters and frequency reference elements has focused attention on the reduction of size, power consumption and price and pushed current research interests towards the manufacturing of a single-chip, integrated RF solution. Vibrating contour-mode MEMS resonators constitute the most promising technology for ultimately realizing this vision. This dissertation presents analytical and experimental results on a new class...

Microfabricated Silicon High Aspect Ratio Flexures for In-Plane Motion

Christopher Guild Keller
Roger T. Howe
John W. Morris, Jr.
Kristofer S.J. Pister
Timothy D. Sands

High aspect ratio microfabricated silicon flexures for in-plane motion were made by three methods: (1) 2-sided timed bulk etching in aqueous potassium hydroxide (KOH), (2) deep reactive ion etching (RB) with Cl2/He, and with SF6 (Bosch process), and (3) the hexsil ...

Micromachined Resonators

Dubravka Bilić
Roger T. Howe
Kristofer S. J. Pister
Roberto Horowitz

In this work, we present approaches of making a micromachined resonators and oscillators. In the first study, we investigated the effects of anchoring on the resonator's performance. Using the Analog Devices BiMEMS integrated technology, double-ended tuning fork resonators have been fabricated with on-chip circuitry. The results show an improvement in the resonator's quality factor when using anchors with multiple contacts to the substrate. Resonators with frequencies up to 3MHz were tested at µTorr pressures to give quality factors as high as 58,000.

In order to reduce...

Miniature-Scale and Micro-Scale Rotary Internal Combustion Engines for Portable Power Systems

Kelvin Fu
A. Carlos Fernandez-Pello
Albert P. Pisano
Kristofer J. Pister
Dorian Liepmann

This work describes the development of both miniature-scale and micro-scale rotary internal combustion engines. This work is part of a project to develop a portable, high specific energy, liquid hydrocarbon-fueled power supply. A Wankel-type rotary engine was chosen for development because of its self-valving operation, planar geometry, and the ability to extract either mechanical or electrical power. To investigate engine behavior and design issues, larger-scale "mini-rotary'' engines have been fabricated from 4 steel. Mini-rotary engine chambers are approximately 1000 mm3 to 1 700 mm3 in...

Algorithms for Distributed Sensor Networks

James D. McLurkin
Kristofer S. J. Pister

A distributed sensor network is many (100-10000) autonomous sensor nodes spread out over a large area. Each node is equipped with a processor, mission-specific sensors, and short-range communications. Local interactions between sensor nodes allow them to reach global conclusions from their data. This work develops algorithms that allow:

The group to establish robust spatial patterns of messages The group to develop a communications network by dividing tasks among themselves Each mote to determine its position in physical space based on their location in the network topology Each mote...

A System Supporting Tiny Networked Sensors

Jason Hill
David Culler
Kristofer Pister

As the post-PC era emerges, several new niches of computer system design are taking shape with characteristics that are quite different from traditional desktop and server regimes. One of the most interesting of these new design regimes is networked sensors. The networked sensor is enabled, in part, by "Moore's Law" pushing computing and storage into a smaller, cheaper, lower-power unit. However, three other trends are equally important: complete systems on a chip, integrated low-power communication, and integrated low-power devices that interact with the physical world. The combination of...

Adversarial Swarm Defense with Decentralized Swarms

Jason Zhou
Kristofer S.J. Pister

The rapid proliferation of unmanned aerial vehicles (UAVs) in both commercial and consumer applications in recent years raises serious concerns of public security, as the versatility of UAVs allow the platform to be easily adapted for malicious activities by adversarial actors. While interdiction methods exist, they are either indiscriminate or are unable to disable a large swarm of drones. Recent work in wireless communications, microelectromechanical systems, fabrication, and multi-agent reinforcement learning make UAV-based counter-UAV systems increasingly feasible - that is, defense...

Analyzing the Prediction Accuracy of Trajectory-Based Models with High-Dimensional Control Policies for Long-term Planning in MBRL

Howard Zhang
Kristofer S.J. Pister

Learning effective policies with model-based reinforcement learning is highly dependent on the accuracy of the dynamics model. Recently, a new parametrization called the trajectory-based model was introduced, which takes in an initial state, a future time index, and control policy parameters, and returns the state at that future time index [3]. This new method has demonstrated improved prediction accuracy in long horizons, increased sample efficiency, and ability to predict the task reward. However, this model has limited transferability to MBRL due to the limited expressivity of its...

Small Autonomous Robot Actuator (SARA): A Solar-powered Wireless MEMS Gripper

Alex Moreno
Kristofer S.J. Pister

Solar-powered actuation of a 15 mN electrostatic MEMS gripper was demonstrated while wirelessly triggered by IEEE 802.15.4 RF signals. The solar-powered gripper was shown to actuate at a rate of 640 um/s. The complete system is composed of three capacitors and three chips: MEMS gripper, microprocessor/crystal-free radio, and solar cell array/high voltage buffer. Control signals for the electrostatic inchworm motors originate from the 3x2x0.3 mm3 chip with an ARM Cortex-M0 microprocessor and are passed through 119V high voltage buffers. Power for all components, including the crystal-free...