Bo Chang - Academia.edu (original) (raw)

Papers by Bo Chang

Materials Science Forum, 2006

... 1College of Mechatronics, Northwestern Polytechnical University, Xi'an 710072, China ...... more ... 1College of Mechatronics, Northwestern Polytechnical University, Xi'an 710072, China ... To enable precise and efficient micro/nano handling, we should: 1) carefully calibrate the ... predictable behavior; 2) to increase the performance of instruments with eg smart material, we can ...

This paper introduces two numerical approaches to model the capillary forces under two different ... more This paper introduces two numerical approaches to model the capillary forces under two different initial conditions: given volume of the liquid and under the capillary condensation. The paper thoroughly analyzes the solutions of both numerical methods. Due to multiple numerical solutions may exist for a given set of parameters, criteria based on the derivative and the second derivative of the solution are proposed to determine the existence and stability of those numerical solutions. The features of those numerical solutions are also carefully discussed. Moreover, the results of two numerical methods are compared in different system parameters for several configurations, including two plates with different volume of liquid between them, a plate and a cone of different incline angle, and a plate and spheres of different radius. Suggestions of the applicability of both methods are given based on the results. To allow calculation of capillary forces between arbitrary shaped objects, th...

This paper studies the hybrid microassembly of 300 μm (L) × 300 μm (W) × 50 μm (H) microchips on ... more This paper studies the hybrid microassembly of 300 μm (L) × 300 μm (W) × 50 μm (H) microchips on sharp edged patterns with different edge heights. Hybrid microassembly combines the robotic pick-and-place technique and the droplet based surface tension driven self-assembly technique, where the robotic pick-and-place handling tool is used for coarse positioning and the droplet self-assembly technique is used for high-accuracy self-alignment. Spreading of the liquid outside the pattern leads to failure in self-alignment. Sharp edge on a solid surface is known for enhancing contact line pinning according to Gibbs inequalities, and therefore inhibit spreading of the liquid. Topological patterns featured with the sharp edge can be used as the receptor site for surface tension driven self-alignment. However, there is little study on how the height of the sharp edge affects the self-alignment process. In this paper, sharp edged topological patterns with five different edge heights: 60 nm, 1...

Journal of Micro-Bio Robotics, 2014

This paper studies the hybrid microassembly of 300 μm (L)×300 μm (W)×30 μm (H) microchips on shar... more This paper studies the hybrid microassembly of 300 μm (L)×300 μm (W)×30 μm (H) microchips on sharp edged patterns with different edge heights. Hybrid microassembly combines the robotic pick-and-place technique and the droplet based surface tension driven selfassembly technique, where the robotic pick-and-place handling tool is used for coarse positioning and the droplet selfassembly technique is used for high-accuracy self-alignment. Spreading of the liquid outside the pattern leads to failure in self-alignment. Sharp edge on a solid surface is known for enabling contact line pinning according to Gibbs inequalities, which prohibits spreading of the liquid. Topological patterns featured with the sharp edge can be used as the receptor site for surface tension driven self-alignment. However, it is unclear how high the sharp edged pattern should be to achieve successful self-alignment in hybrid microassembly. In this paper, sharp edged topological patterns with five different edge heights: 70 nm, 140 nm, 280 nm, 540 nm and 1,050 nm, have been fabricated and tested with water to investigate the influence of the edge height on the hybrid microassembly. The experimental results indicate the edge height affects both the contact line pinning and the selfalignment process. Water droplet can successfully pin at the edge of patterns higher than 280 nm. Self-alignment can reach 100 % success rate on the patterns with edge height of 1 μm when the initial placement error is below 150 μm.

2006 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2006

This paper presents a hybrid microhandling strategy that combines robotic-based contact micromani... more This paper presents a hybrid microhandling strategy that combines robotic-based contact micromanipulation and capillary self-alignment. The novel approach combines the flexibility and dexterity of robotic microhandling technologies and the advantages of self-alignment where adhesion forces are utilized to help the placement of micro objects. Besides theoretical modelling, the paper presents experimental studies on hybrid placement of 300times300times100 mum microparts and demonstrates 3D construction of an 8-piece microstructure using the hybrid method

Journal of Microelectromechanical Systems, 2000

Surface tension-driven self-alignment is reported to be very accurate when the chip and receptor ... more Surface tension-driven self-alignment is reported to be very accurate when the chip and receptor site are well-defined. This paper investigates surface tension-driven selfalignment of microchips on low-precision receptors through experimental studies and theoretical analysis to understand the relation between alignment accuracy and the precision of the receptor edges. Three different types of low-precision receptors have been designed and fabricated to study the alignment accuracy: 1) receptors with a single triangular defect pointing outward or inward with amplitude of 10, 30, and 60 µm and corresponding width of 20, 60, and 120 µm; 2) receptors with constant triangular edge jaggedness with amplitude of 2, 4, 5, and 15 µm; and 3) receptors with random triangular edge jaggedness with amplitude of 2, 4, and 8 µm. The DI water is used as the self-alignment medium. The alignment accuracy has been closely measured with an environmental scanning electron microscope. Numerical simulators, e.g., surface evolver have been used to analyze the results. The experimental results show that low-precision receptors impair alignment accuracy in a much lesser degree than the scale of the defects on a receptor.

Applied Physics Letters, 2012

Personal and Ubiquitous Computing, 2011

Fluid driven self-alignment is a low cost alternative to fast but relatively inaccurate robotic p... more Fluid driven self-alignment is a low cost alternative to fast but relatively inaccurate robotic pickand-place assembly of micro-fabricated components. This fluidic self-alignment technique relies on a hydrophobic-hydrophilic pattern on the surface of the receiving substrate, which confines a fluid to a receptor site. When a micro-component is dropped on the fluid capillary forces drive the assembly process, resulting in accurate

Proceedings of SPIE - The International Society for Optical Engineering

With the trend of miniaturization of mechatronics products, the demands on microassembly increase... more With the trend of miniaturization of mechatronics products, the demands on microassembly increase substantially. Due to the scaling effect, handling and planning in microassembly is considerably different from those in conventional assembly. One important issue is to study how the environmental parameters will shape the scaling effect and consequently the handling of micro parts. A controlled environment will enable a better understanding of the handling tasks in microassembly and consequently provide a necessary tool for the development of model-based microassembly methods. Moreover, environmental parameters can affect the performance of microassembly system. This paper will present our progress of developing a microassembly station with controlled environment. The microassembly station includes a microassembly platform that is able to mount various tools such as microscopes, mobile stages, micro grippers, etc. The microassembly platform is installed in a controlled environment where temperature and humidity can be controlled, and mechanical vibration is damped. Such a microassembly station facilitates researching microassembly methods and techniques under different environmental conditions. Early study of the effects of environmental parameters to microassembly system and pick-and-place operation is reported as well.

ABSTRACT This paper proposes a hybrid microassembly technique for massively parallel assembly of ... more ABSTRACT This paper proposes a hybrid microassembly technique for massively parallel assembly of 200μm × 200μm × 30μm SU-8 chips. The hybrid microassembly technique combines the robotic pick-and-place technique and water mist induced self-assembly technique. The robotic handling tool is used to place microchips roughly on chips of the same size at a fast speed, and then water mist composed of microscopic droplets is delivered to achieve high accuracy and massively parallel alignments. The results indicate the hybrid assembly technique is promising for assembly of microchips. A 200μm × 200μm × 70μm SU-8 chip is assembled on the top of another SU-8 chip of the same size; where the success rate can reach 80% with bias as high as 130μm in x- and y directions. We have demonstrated that the proposed technique in assembly a matrix of 30 200μm × 200μm SU-8 chips. The results also show that alignment can reach sub micrometer accuracy.

2010 IEEE International Conference on Automation Science and Engineering, 2010

This paper reports a novel process that positions RFID chips on segmented artificial antenna patt... more This paper reports a novel process that positions RFID chips on segmented artificial antenna pattern using hybrid assembly technology. A droplet of water is firstly dispensed to an artificial pattern composed of four pads. Then a 730×730μm RFID chip with four bumps of 20μm in height is released onto the artificial pattern using a robotic microgripper. Finally the RFID chip

Scientific reports, 2015

Alignment of microchips with receptors is an important process step in the construction of integr... more Alignment of microchips with receptors is an important process step in the construction of integrated micro- and nanosystems for emerging technologies, and facilitating alignment by spontaneous self-assembly processes is highly desired. Previously, capillary self-alignment of microchips driven by surface tension effects on patterned surfaces has been reported, where it was essential for microchips to have sufficient overlap with receptor sites. Here we demonstrate for the first time capillary self-transport and self-alignment of microchips, where microchips are initially placed outside the corresponding receptor sites and can be self-transported by capillary force to the receptor sites followed by self-alignment. The surface consists of hydrophilic silicon receptor sites surrounded by superhydrophobic black silicon. Rain-induced microscopic droplets are used to form the meniscus for the self-transport and self-alignment. The boundary conditions for the self-transport have been explo...

Proceedings of the ... IEEE/RSJ International Conference on Intelligent Robots and Systems. IEEE/RSJ International Conference on Intelligent Robots and Systems

this paper discusses capillary self-alignment assisted hybrid microassembly of chips on low preci... more this paper discusses capillary self-alignment assisted hybrid microassembly of chips on low precision patterns, in both the precision of the dimension and the precision of the edge smoothness. Special segmented patterns having jagged edges have been purposely designed and fabricated to mimic some real-world RFID antennas. Experimental tests have been carried out to investigate influence of the dimension and the edge jaggedness on the yield and accuracy of the self-alignment, using 730 × 730 × 70 µm RFID chips as the test samples. The results show that the self- alignment occurs reliably with releasing bias less than 300 µm in both horizontal axes, despite the variation in size of the segmented pattern and edge jaggedness. However, both the dimension and the edge jaggedness affect the alignment accuracy.

Proceedings, 2005 IEEE/ASME International Conference on Advanced Intelligent Mechatronics., 2005

This paper presents a novel 6 DOF (degree-offreedom) piezoelectric micro gripping/handling system... more This paper presents a novel 6 DOF (degree-offreedom) piezoelectric micro gripping/handling system for automatic dexterous manipulation and inspection of micro optoelectronic components. The purpose of the system is to pick-and-place and align microparts having size of 300 to 400 µm square. The alignment task includes both translational alignment for field-of-view and focusing, and rotational alignment for uniform focusing. All six actuation axes are controlled based on strain gauge sensor feedback. A networkbased control system is used for automatic control of the gripper. The control system includes three hierarchical layers: actuator control layer, motion planning layer, and mission layer. Visual servoing is applied in automatic handling. The performance of the system is demonstrated in a fully automated inspection task.

2010 International Symposium on Micro-NanoMechatronics and Human Science, 2010

ABSTRACT This paper reports a novel and versatile hybrid microassembly technique that applies wat... more ABSTRACT This paper reports a novel and versatile hybrid microassembly technique that applies water mist on the surface of microparts to assist alignment of microchips. This technique combines the traditional robotic pick-and-place technique and self-assembly technique. Two different approaches are studied: 1) mist-last where a 200μm × 200μm × 70μm SU-8 chip is placed roughly on another chip of the same size using a microgripper and then water mist is delivered to achieve self-alignment; 2) mist-first where water mist is delivered before the releasing of a chip near the target. The second approach is further studied to examine the maximum tolerance of placement error and placement of chips on hydrophilic/hydrophobic patterns. The experimental results indicate the proposed technique is reliable and versatile for stacking and assembling microchips. a 200μm × 200μm × 70μm SU-8 chip was assembled on the top of another SU-8 chip of the same dimensions, where the success rate can reach 75% with bias as high as 180μm. Microparts of size 200μm × 200μm × 70μm can be successfully assembled on hydrophilic/hydrophobic patterns.

Journal of Micromechanics and Microengineering, 2011

This paper reports an in-depth study of a water-droplet-assisted self-alignment technique that se... more This paper reports an in-depth study of a water-droplet-assisted self-alignment technique that self-aligns radio frequency identification (RFID) dies on four-pad patterns. The segmented structure of four hydrophilic pads on a hydrophobic substrate brings freedom to the design of the electrical functionality and the surface functionality. The paper investigates the influence of the key parameters that may affect the self-alignment in theory and experiment. The theoretical model justifies that RFID dies can be reliably aligned on the segmented four-pad pattern even when the initial placement error is as large as 50% of the size of the die and the gap between the four pads is about 10% of the size of the die. A method has been introduced to estimate the sufficient droplet volume for self-alignment. A series of experiments have been carried out to verify the results of the model. The experiments indicate that the self-alignment between the 730 × 730 μm RFID dies and the pattern occurs reliably when the releasing bias between the RFID die and antenna is less than 400 μm for patterns with 50 and 100 μm gaps, and successful self-alignment is possible even with greater bias of 500 μm.

Journal of Micromechanics and Microengineering, 2011

This paper reports a novel and versatile water droplet self-alignment technique where the water i... more This paper reports a novel and versatile water droplet self-alignment technique where the water is delivered in mist form onto the assembly site. The droplet forming process has been carefully investigated using machine vision, where each individual droplet on the microchip surface can be identified and the volume per surface area can be calibrated at a specific time. The result reveals that the volume of water droplets on the assembly surface grows linearly as a function of time. Self-alignment based on the mist-induced droplets has been studied, where a robotic microgripper is used to deliver the microchips on the assembly site. The paper also investigates the maximum tolerance of the initial placement error in stacking SU-8 chips 200 × 200 × 70 μm in size, and the possibility of stacking two SU-8 chips of different dimensions using the proposed self-alignment technique. Moreover, self-alignment of chips on hydrophilic/hydrophobic patterns covered by mist-induced water droplets has been studied. The experimental results indicate that this novel self-alignment technique is very promising. Furthermore, a statistical model has been used to validate the experimental results.

Applied Physics Letters, 2011

This letter describes a capillary-driven self-assembly technique using oleophilic/oleophobic patt... more This letter describes a capillary-driven self-assembly technique using oleophilic/oleophobic patterned surface and adhesive in ambient air environment. We use a topographical microstructure of porous ormocer functionalized with a fluorinated trichlorosilane for the oleophobic area and gold patterns for the oleophilic area. The resulted oleophilic/oleophobic patterns show significant wettability contrast for adhesive (Delo 18507), with a contact angle of 119° on

Materials Science Forum, 2006

Journal of Micro-Bio Robotics, 2014

2006 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2006

Journal of Microelectromechanical Systems, 2000

Applied Physics Letters, 2012

Personal and Ubiquitous Computing, 2011

Proceedings of SPIE - The International Society for Optical Engineering

2010 IEEE International Conference on Automation Science and Engineering, 2010

Scientific reports, 2015

Proceedings of the ... IEEE/RSJ International Conference on Intelligent Robots and Systems. IEEE/RSJ International Conference on Intelligent Robots and Systems

Proceedings, 2005 IEEE/ASME International Conference on Advanced Intelligent Mechatronics., 2005

2010 International Symposium on Micro-NanoMechatronics and Human Science, 2010

Journal of Micromechanics and Microengineering, 2011

Applied Physics Letters, 2011