AFAM: An Articulated Four Axes Microrobot for Nanoscale Applications

Abstract

This paper presents a microassembled robot called the Articulated Four Axes Microrobot (AFAM). Target application areas include micro and nano part manipulation and probing. The robot consists of a cantilever actuated along four axes: in-place <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$X, Y$</tex></formula> and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$YAW$</tex> </formula> ; out-of-plane pitch. The microrobot size spans a total volume of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$3~{\rm mm}\times 1.5~{\rm mm}\times 1~{\rm mm}$</tex></formula> ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$XYZ$</tex> </formula> ), and operates within a workspace envelope of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$50~\mu{\rm m}\times 50~\mu{\rm m}\times 75~\mu{\rm m}$</tex> </formula> ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$XYZ$</tex> </formula> ). This is by far the largest operating envelope of any micropositioner with nonplanar dexterity. As a result it can be classified as a new type of three-dimensional microrobot and a candidate for miniaturizing top-down assembly systems to dimensions under <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$1~{\rm cm}^{3}$</tex></formula> . A key feature in this design is a cable-like microwire that transforms in-plane actuator displacement into out-of-plane pitch and yaw motion (via flexure joints). Finite-element analysis simulation followed by microfabrication and assembly processes developed to prototype the designs are described. The microrobot is designed to carry an AFM tip as the end effector and accomplish nanoindentation on a polymer surface. The tip attachment technique and nanoindentation experiments have also been described in this paper. Open loop precision has been characterized using a laser interferometer which measured an average resolution of 50 nm along <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$XYZ$</tex> </formula> , repeatability of 100 nm and accuracy of 500 nm. Experiments to determine microrobot reliability are also presented.