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Packaging electronic devices within electronic textiles and fibrous substrates requires an understanding of how fibers interact with circuit components in different operating conditions. In this paper, we use microeletromechanical (MEMS) devices to put devices in electrical contact with fine wires. We characterize the electronic properties of MEMS-to-wire contacts and discuss general guidelines for optimizing the design of these grippers and potential MEMS-based circuits. We then demonstrate how these grippers can act as non-rigid circuit components that effectively transfer power to devices such as LEDs. Analysis shows that our grippers are suitable conductors (under 150 Ohms) under standard operating temperatures (25-100 deg. C) with potential for use as sensors for current overflow or temperature. Methods such as parylene deposition and silver epoxy to stabilize MEMS performance are briefly discussed and explored. 

Direct write Inkjet Printing is a versatile additive manufacturing technology that allows for the fabrication of multiscale structures with dimensions spanning from nano to cm scale. This is made possible due to the development of novel dispensing tools, enabling controlled and precise deposition of fluid with a wide range of viscosities (1 – 50 000 mPas) in nanoliter volumes. As a result, Inkjet printing has been recognized as a potential low-cost alternative for several established manufacturing methods, including cleanroom fabrication. In this paper, we present a characterization study of PEDOT: PSS polymer ink deposition printing process realized with the help of an automated, custom Direct Write Inkjet system. PEDOT: PSS is a highly conductive ink that possesses good film forming capabilities. Applications thus include printing thin films on flexible substrates for tactile (touch) sensors. We applied the Taguchi Design of Experiment (DOE) method to produce the optimal set of PEDOT:PSS ink dispensing parameters, to study their influence on the resulting ink droplet diameter. We experimentally determined that the desired outcome of a printed thin film with minimum thickness is directly related to 1) the minimum volume of dispensed fluid and 2) the presence of a preprocessing step, namely air plasma treatment of the Kapton substrate. Results show that an ink deposit with a minimum diameter of 482 μm, and a thin film with approximately 300 nm thickness were produced with good repeatability.

 

The placement of SMD components is usually performed with Cartesian type robots, a task known as pick-and-place (P&P). Small Selective Compliance Articulated Robot Arm (SCARA) robots are also growing in popularity for this use because of their quick and accurate performance. This paper describes the use of the Lean Robotic Micromanufacturing (LRM) framework applied on a large, 10kg payload, industrial SCARA robot for PCB assembly. The LRM framework guided the precision evaluation of the PCB assembly process and provided a prediction of the placement precision and yield. We experimentally evaluated the repeatability of the system, as well as the resulting collective errors during the assembly. Results confirm that the P&P task can achieve the required assembly tolerance of 200 microns without employing closed-loop visual servoing, therefore considerably decreasing the system complexity and assembly time.

 

Enhancing physical human-robot interaction requires the improvement in the tactile perception of physical touch. Robot skin sensors exhibiting piezoresistive behavior can be used in conjunction with collaborative robots. In past work, fabrication of these tactile arrays was done using cleanroom techniques such as spin coating, photolithography, sputtering, wet and dry etching onto flexible polymers. In this paper, we present an addictive, non-cleanroom improved process of depositing PEDOT: PSS, which is the organic polymer responsible for the piezoresistive phenomenon of the robot skin sensor arrays. This publication details the patterning of the robot skin sensor structures and the adaptation of the inkjet printing technology to the fabrication process. This increases the possibility of scaling the production output while reducing the cleanroom fabrication cost and time from an approximately five-hour PEDOT: PSS deposition process to five minutes. Furthermore, the testing of these skin sensor arrays is carried out on a testing station equipped with a force plunger and an integrated circuit designed to provide perception feedback on various force load profiles controlled in an automated process. The results show uniform deposition of the PEDOT: PSS, consistent resistance measurement, and appropriate tactile response across an array of 16 sensors.

 

In modern industrial manufacturing processes, robotic manipulators are routinely used in the assembly, packaging, and material handling operations. During production, changing end-of-arm tooling is frequently necessary for process flexibility and reuse of robotic resources. In conventional operation, a tool changer is sometimes employed to load and unload end-effectors, however, the robot must be manually taught to locate the tool changers by operators via a teach pendant. During tool change teaching, the operator takes considerable effort and time to align the master and tool side of the coupler by adjusting the motion speed of the robotic arm and observing the alignment from different viewpoints. In this paper, a custom robotic system, the NeXus, was programmed to locate and change tools automatically via an RGB-D camera. The NeXus was configured as a multi-robot system for multiple tasks including assembly, bonding, and 3D printing of sensor arrays, solar cells, and microrobot prototypes. Thus, different tools are employed by an industrial robotic arm to position grippers, printers, and other types of end-effectors in the workspace. To improve the precision and cycle-time of the robotic tool change, we mounted an eye-in-hand RGB-D camera and employed visual servoing to automate the tool change process. We then compared the teaching time of the tool location using this system and compared the cycle time with those of 6 human operators in the manual mode. We concluded that the tool location time in automated mode, on average, more than two times lower than the expert human operators. 

Recent advancements in additive manufacturing such as Direct Write Inkjet printing introduced novel tools that allow controlled and precise deposition of fluid in nano-liter volumes, enabling fabrication of multiscale structures with submillimeter dimensions. Applications include fabrication of flexible electronics, sensors, and assembly of Micro-Electro-Mechanical Systems (MEMS). Critical challenges remain in the control of fluid deposition parameters during Inkjet printing to meet specific dimensional footprints at the microscale necessary for the assembly process of microscale structures. In this paper we characterize an adhesive deposition printing process with a piezo-electric dispenser of nano-liter volumes. Applications include the controlled delivery of high viscosity Ultraviolet (UV) and thermal curable adhesives for the assembly of the MEMS structures. We applied the Taguchi Design of Experiment (DOE) method to determine an optimal set of process parameters required to minimize the size of adhesive printed features on a silicon substrate with good reliability and repeatability of the deposition process. Experimental results demonstrate repeatable deposition of UV adhesive features with 150 μm diameter on the silicon substrate. Based on the observed wettability effect of adhesive printed onto different substrates we propose a solution for further reduction of the deposit-substrate contact area for microassembly optimization.