Deepkishore Mukhopadhyay

Bio: Deepkishore Mukhopadhyay is an academic researcher from Argonne National Laboratory. The author has contributed to research in topics: Microelectromechanical systems & Kinematics. The author has an hindex of 7, co-authored 21 publications receiving 1609 citations. Previous affiliations of Deepkishore Mukhopadhyay include University of Chicago & University of Illinois at Urbana–Champaign.

High-resolution electrohydrodynamic jet printing

Abstract: Efforts to adapt and extend graphic arts printing techniques for demanding device applications in electronics, biotechnology and microelectromechanical systems have grown rapidly in recent years. Here, we describe the use of electrohydrodynamically induced fluid flows through fine microcapillary nozzles for jet printing of patterns and functional devices with submicrometre resolution. Key aspects of the physics of this approach, which has some features in common with related but comparatively low-resolution techniques for graphic arts, are revealed through direct high-speed imaging of the droplet formation processes. Printing of complex patterns of inks, ranging from insulating and conducting polymers, to solution suspensions of silicon nanoparticles and rods, to single-walled carbon nanotubes, using integrated computer-controlled printer systems illustrates some of the capabilities. High-resolution printed metal interconnects, electrodes and probing pads for representative circuit patterns and functional transistors with critical dimensions as small as 1 μm demonstrate potential applications in printed electronics.

Analysis of thermal errors in a high-speed micro-milling spindle

Abstract: Thermally induced errors account for the majority of fabrication accuracy loss in an uncompensated machine tool. This issue is particularly relevant in the micro-machining arena due to the comparable size of thermal errors and the characteristic dimensions of the parts under fabrication. A spindle of a micro-milling machine tool is one of the main sources of thermal errors. Other sources of thermal errors include drive elements like linear motors and bearings, the machining process itself and external thermal influences such as variation in ambient temperature. The basic strategy for alleviating the magnitude of these thermal errors can be achieved by thermal desensitization, control and compensation within the machine tool. This paper describes a spindle growth compensation scheme that aims towards reducing its thermally-induced machining errors. The implementation of this scheme is simple in nature and it can be easily and quickly executed in an industrial environment with minimal investment of manpower and component modifications. Initially a finite element analysis (FEA) is conducted on the spindle assembly. This FEA correlates the temperature rise, due to heating from the spindle bearings and the motor, to the resulting structural deformation. Additionally, the structural deformation of the spindle along with temperature change at its various critical points is experimentally obtained by a system of thermocouples and capacitance gages. The experimental values of the temperature changes and the structural deformation of the spindle qualitatively agree well with the results obtained by FEA. Consequently, a thermal displacement model of the high-speed micro-milling spindle is formulated from the previously obtained experimental results that effectively predict the spindle displacement under varying spindle speeds. The implementation of this model in the machine tool under investigation is expected to reduce its thermally induced spindle displacement by 80%, from 6 microns to less than 1 micron in a randomly generated test with varying spindle speeds.

High resolution electrohydrodynamic jet printing for manufacturing systems

Abstract: Provided are high-resolution electrohydrodynamic inkjet (e-jet) printing systems and related methods for printing functional materials on a substrate surface. In an embodiment, a nozzle with an ejection orifice that dispenses a printing fluid faces a surface that is to be printed. The nozzle is electrically connected to a voltage source that applies an electric charge to the fluid in the nozzle to controllably deposit the printing fluid on the surface. In an aspect, a nozzle that dispenses printing fluid has a small ejection orifice, such as an orifice with an area less than 700 μm 2 and is capable of printing nanofeatures or microfeatures. In an embodiment the nozzle is an integrated-electrode nozzle system that is directly connected to an electrode and a counter-electrode. The systems and methods provide printing resolutions that can encompass the sub-micron range.

A SOI-MEMS-based 3-DOF planar parallel-kinematics nanopositioning stage

Abstract: This paper presents the design, kinematic and dynamic analysis, fabrication and characterization of a monolithic micro/nanopositioning three degrees-of-freedom (DOF) (XYθ) stage. The design of the proposed MEMS (micro-electro-mechanical system) stage is based on a parallel-kinematic mechanism (PKM) scheme that allows for translation in the XY plane and rotation about the Z axis, an increased motion range, and linear kinematics in the operating region (or work area) of the stage. The truss-like structure of the PKM results in higher modal frequencies by increasing the structural stiffness and reducing the moving mass of the stage. The stage is fabricated on a silicon-on-insulator (SOI) wafer using surface micromachining and deep reactive ion etching (DRIE) processes. Three sets of electrostatic linear comb drives jointly actuate the mechanism to produce motion in the X, Y and θ (rotation) directions. The fabricated stage provides a motion range of 18 μm and 1.72° at a driving voltage of 85 V. The resonant frequency of the stage under ambient conditions is 465 Hz. Additionally a high Q factor (∼66) is achieved from this parallel-kinematics mechanism design.

Design, fabrication and testing of a silicon-on-insulator (SOI) MEMS parallel kinematics XY stage

Abstract: This paper presents the design, kinematics, fabrication and characterization of a monolithic micro positioning two degree-of-freedom translational (XY) stage. The design of the proposed MEMS (micro-electro-mechanical system) stage is based on a parallel kinematics mechanism (PKM). The stage is fabricated on a silicon-on-insulator (SOI) substrate. The PKM design decouples the motion in the XY directions. The design restricts rotations in the XY plane while allowing for an increased motion range and produces linear kinematics in the operating region (or workspace) of the stage. The truss-like structure of the PKM also results in increased stiffness by reducing the mass of the stage. The stage is fabricated on a silicon-on-insulator (SOI) wafer using surface micromachining and a deep reactive ion etching (DRIE) process. Two sets of electrostatic linear comb drives are used to actuate the stage mechanism in the X and Y directions. The fabricated stage provides a motion range of more than 15 µm in each direction at a driving voltage of 45 V. The resonant frequency of the stage under ambient conditions is 960 Hz. A high Q factor (~100) is achieved from this parallel kinematics mechanism design.

Polymers for 3D Printing and Customized Additive Manufacturing

Abstract: Additive manufacturing (AM) alias 3D printing translates computer-aided design (CAD) virtual 3D models into physical objects. By digital slicing of CAD, 3D scan, or tomography data, AM builds objects layer by layer without the need for molds or machining. AM enables decentralized fabrication of customized objects on demand by exploiting digital information storage and retrieval via the Internet. The ongoing transition from rapid prototyping to rapid manufacturing prompts new challenges for mechanical engineers and materials scientists alike. Because polymers are by far the most utilized class of materials for AM, this Review focuses on polymer processing and the development of polymers and advanced polymer systems specifically for AM. AM techniques covered include vat photopolymerization (stereolithography), powder bed fusion (SLS), material and binder jetting (inkjet and aerosol 3D printing), sheet lamination (LOM), extrusion (FDM, 3D dispensing, 3D fiber deposition, and 3D plotting), and 3D bioprinting....

Inkjet Printing—Process and Its Applications

Abstract: In this Progress Report we provide an update on recent developments in inkjet printing technology and its applications, which include organic thin-film transistors, light-emitting diodes, solar cells, conductive structures, memory devices, sensors, and biological/pharmaceutical tasks. Various classes of materials and device types are in turn examined and an opinion is offered about the nature of the progress that has been achieved.

Stretchable form of single crystal silicon for high performance electronics on rubber substrates

Abstract: The present invention provides stretchable, and optionally printable, semiconductors and electronic circuits capable of providing good performance when stretched, compressed, flexed or otherwise deformed. Stretchable semiconductors and electronic circuits of the present invention preferred for some applications are flexible, in addition to being stretchable, and thus are capable of significant elongation, flexing, bending or other deformation along one or more axes. Further, stretchable semiconductors and electronic circuits of the present invention may be adapted to a wide range of device configurations to provide fully flexible electronic and optoelectronic devices.

Stretchable active-matrix organic light-emitting diode display using printable elastic conductors

Abstract: Stretchability will significantly expand the applications scope of electronics, particularly for large-area electronic displays, sensors and actuators. Unlike for conventional devices, stretchable electronics can cover arbitrary surfaces and movable parts. However, a large hurdle is the manufacture of large-area highly stretchable electrical wirings with high conductivity. Here, we describe the manufacture of printable elastic conductors comprising single-walled carbon nanotubes (SWNTs) uniformly dispersed in a fluorinated rubber. Using an ionic liquid and jet-milling, we produce long and fine SWNT bundles that can form well-developed conducting networks in the rubber. Conductivity of more than 100 S cm(-1) and stretchability of more than 100% are obtained. Making full use of this extraordinary conductivity, we constructed a rubber-like stretchable active-matrix display comprising integrated printed elastic conductors, organic transistors and organic light-emitting diodes. The display could be stretched by 30-50% and spread over a hemisphere without any mechanical or electrical damage.

Organic thin-film transistors.

Abstract: Over the past 20 years, organic transistors have developed from a laboratory curiosity to a commercially viable technology. This critical review provides a short summary of several important aspects of organic transistors, including materials, microstructure, carrier transport, manufacturing, electrical properties, and performance limitations (200 references).