Texas Tech wins award for Microbotic Chess Player

Sandia National Laboratories and the MEMS Technologies Department is pleased to announce the 2010 winners of the MEMS University Alliance Design Competition !!!

“NOVEL DESIGN” CATEGORY – Texas Tech University

This year’s competition was once again very competitive. Each year the designs get better and the associated white papers get more professional. Thank you all for participating and for making this year’s competition so successful.

We look forward to you coming out to Sandia on May 18 to present your designs and to interact with Sandia MEMS experts.

Sandia National Laboratories

University Alliance Design Competition 2010

Texas Tech University – Novel Design Entry

MICROBOTIC

Chess Player

Texas Tech University

I. Abstract

This white paper describes the design of a Microbotic Chess Player system developed using the SUMMiT V fabrication process. This design consists of the World’s Smallest Chess Set and is capable of being played using on-chip robotic manipulator. A 2-DOF microrobotic arm is driven by long travel actuators. In addition to furthering research in the area of micromanipulation, this chess player could prove to be fascinating for chess playing students over a range of education levels. The long-travel, bi-directional linear actuator is designed to have total travel of 405μm with a minimum step size of 9μm. A series of experimental procedures are proposed for complete characterization and testing the functionality of the fabricated system.

II. Objective

The objective is to produce a playable micro-Chess game by:  Designing a checkerboard having chess pieces capable of being maneuvered using an on-chip 2-axis manipulator. Developing a 2-axis positioning system. Developing a bi-directional long travel actuator capable of hovering over the entire span of the chess board.

III. Introduction

In Microelectromechanical Systems (MEMS), micro- and nanometer-sized object manipulation has found importance and applications in many areas. For instance, manipulation of carbon nanotubes and nano-particles using atomic force microscope (AFM) [1, 2] and getting the visual feedback while in a scanning electron microscope (SEM) or transmission electron microscope (TEM) [3,4,5] has been demonstrated. Microassembly is necessary for sub-centimeter-scale microsystems that incorporate solid-state light sources such as LEDs or lasers into MEMS optical applications. The development of linear actuators has made possible MEMS devices for micro/nano positioning, biological cell probing, medical devices and micro-scale optical systems. There are always tradeoffs between minimum and maximum displacement, force, and degrees of freedom to be considered when designing such systems. Thermal actuators have proven to be a robust actuation method in surface micromachined MEMS. They generate a relatively large output force and sufficient displacement at low actuation voltages, which make them an attractive alternative to more traditional electrostatic actuation methods.

In an attempt to develop synergy between the Texas Tech University (TTU) MEMS group and other academic institutes on campus, we initiated contact with TTU‟s Susan Polgar Institute for Chess Excellence (SPICE). Grand Master Susan Polgar, is one of the top chess players in the world, and heads this institute. Chess, which has its origins in the 7th century, is an international game that is widely played across nearly all age groups. Using the game of chess, we will demonstrate the capability of a novel, 2-axis micro-manipulator for moving and positioning microstructures. In addition to being an important advancement in on-chip manipulators, the system will be the nexus for educational endeavors, by engaging students at all levels. This manipulator is designed to produce long travel (100‟s of microns) in small step sizes (~10 microns) with minimum power requirements, i.e. zero power latching. The design will be fabricated using the Sandia Ultra-planer, Multi-level MEMS Technology 5 (SUMMiT VTM) process. Exploiting the strengths of this five-layer process, we designed the chess board, pieces, and the manipulator to move the pieces over the whole span of the chess board. The manipulator is comprised of a bi-directional, two-axis MEMS positioning system and bi-directional actuators.

IV. Description

Device Design

The AutoCAD design for the Microbotic Chess Player is shown in Figure 1. The system can be broken down into three key components: (1) chess board and pieces, (2) two-axis MEMS positioning system, for enabling 2-DOF motion and (3), and two, long travel bi-directional linear ratcheting actuators.

Chess Board and Pieces

The chess board (Figure 2) is an eight-by-eight grid with total dimensions of 435μm x 435μm. The colors of the sixty-four squares alternate and are made using the patterned and un-patterned Poly0 layer for making “light squares” and “dark squares,” respectively. The chess board has sixteen chess pieces on each side. Each piece has its shape in the Poly2 layer with a Poly3 layer stub attached to it. This stub acts as an end-effector handling area, where the manipulator end will interface with the chess piece. Figure 4 shows the 3-D model and a cross-section view of a chess piece. After the sacrificial oxide release, the pieces will still be attached to the substrate through a 1μm diameter Poly1 via connected to Poly0. This via is just enough to hold the piece in-place, post-release.

The end-effector (Figure 5) has a circular area which is held over the board using a Poly4 cantilever and comes into contact with the Poly3 stub on each chess piece, as shown in Figure 6. The end-effector is provided with small semicircular protrusions which will minimize contact area and reduce stiction. An external path has been provided along each side of the chess board which allows movement of chess pieces without having to jump other pieces. This path has a boundary formed using Poly2 which acts as a stop and doesn‟t allow chess pieces to exit the board. The dimensions of the path are such that 15 knocked-off micro-chess pieces can be placed outside the area of the chess board.

Figures 7 and 8 show the SEM images of a chess board and pieces fabricated on the 2009 Texas Tech University (TTU) Sandia design competition chip. The board was 1 mm x 1mm square with 100 μm diameter pieces. This version was designed for being played using an off-chip microgripper capable of being operated in 3-dimensions with micron scale control. A sharp probe or a microgripper can be used to pick and place the chess pieces. The present version is designed to be played using the on-chip manipulator. The area of the chess board and the pieces have been scaled down by a factor of 2 (in both X and Y), compared to the previous version, to lessen the travel required of the manipulator.