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Full-Text Articles in Engineering Science and Materials

Influence Of Flow Rate, Nozzle Speed, Pitch And The Number Of Passes On The Thickness Of S1805 Photoresist In Suss Microtec As8 Spray Coater, Rohan Sanghvi, Gyuseok Kim Oct 2019

Influence Of Flow Rate, Nozzle Speed, Pitch And The Number Of Passes On The Thickness Of S1805 Photoresist In Suss Microtec As8 Spray Coater, Rohan Sanghvi, Gyuseok Kim

Tool Data

S1805 positive photoresist has been deposited on single crystalline Si wafers using a Suss MicroTec Alta Spray. The influence of flow rate, nozzle speed, pitch and number of passes on the thickness of the photoresist was studied. Results show that the thickness of S1805 is linearly proportional to the flow rate and number of passes, and inversely proportional to the nozzle speed and pitch.


Correction Of Pattern Size Deviations In The Fabrication Of Photomasks Made With A Laser Direct-Writer, Ningzhi Xie, George Patrick Watson Oct 2019

Correction Of Pattern Size Deviations In The Fabrication Of Photomasks Made With A Laser Direct-Writer, Ningzhi Xie, George Patrick Watson

Protocols and Reports

When using Heidelberg DWL66+ laser writer to fabricate the photomask, the pattern feature dimensions may have deviations. These deviations can be caused by the lithography process and the undercut in the metal etch process. The same deviation value of 0.8µm was found to appear in all the patterns independent of the pattern original size and local pattern density. To overcome this universal deviation, a universal bias is suggested to be applied to the original patterns during the data preparation for the lithography process. In order to ensure this pre-exposure bias method can work, both the laser direct-write exposure conditions ...


Progress Report I: Fabrication Of Nanopores In Silicon Nitride Membranes Using Self-Assembly Of Ps-B-Pmma, Unnati Joshi, Vishal Venkatesh, Hiromichi Yamamoto Mar 2019

Progress Report I: Fabrication Of Nanopores In Silicon Nitride Membranes Using Self-Assembly Of Ps-B-Pmma, Unnati Joshi, Vishal Venkatesh, Hiromichi Yamamoto

Protocols and Reports

This progress report describes fabrication of silicon nitride membranes from Si wafers using cleanroom techniques, and of nanopore preparation via a self-assembled PS-b-PMMA film. A 36.9 µm thick membrane is successfully prepared by KOH wet etching. The membrane is a layered structure of 36.8 µm thick Si and 116 nm thick silicon nitride. It is also exhibited that in the 47 nm thick PS-b-PMMA film, the nanopore structure is observed in the vicinity of a dust particle, but most of the area indicates lamellar domain structure. The thickness of PS-b-PMMA film will ...


Inkjet Printing Of Ag Nanoparticles Using Dimatix Inkjet Printer, No 2, Ming Yuan Chuang May 2017

Inkjet Printing Of Ag Nanoparticles Using Dimatix Inkjet Printer, No 2, Ming Yuan Chuang

Protocols and Reports

This report describes the rheological analysisof the present Ag nanoparticle ink, and confirms that it is suitable for the piezoelectric drop-on-demand printing for both of 1 pL and 10 pL cartridges. The satellite drops and the splashing on the substrate are also discussed for optimization of the nozzle temperature and the jetting voltage. The minimum horizontal and vertical line widths are shown to be 30 and 40 µm, respectively, but the average minimum single line width is estimated to be ~50 µm. The non-uniform width lines are suggested to arise from the bulge instability. Furthermore, it is indicated that the ...


Flexible, Photopatterned, Colloidal Cdse Semiconductor Nanocrystal Integrated Circuits, Franklin Scott Stinner Jan 2017

Flexible, Photopatterned, Colloidal Cdse Semiconductor Nanocrystal Integrated Circuits, Franklin Scott Stinner

Publicly Accessible Penn Dissertations

As semiconductor manufacturing pushes towards smaller and faster transistors, a parallel goal exists to create transistors which are not nearly as small. These transistors are not intended to match the performance of traditional crystalline semiconductors; they are designed to be significantly lower in cost and manufactured using methods that can make them physically flexible for applications where form is more important than speed. One of the developing technologies for this application is semiconductor nanocrystals.

We first explore methods to develop CdSe nanocrystal semiconducting “inks” into large-scale, high-speed integrated circuits. We demonstrate photopatterned transistors with mobilities of 10 cm2/Vs on ...


Microwave Impedance Microscopy Of Nanostructured Carbon, Timothy Scott Jones Jan 2016

Microwave Impedance Microscopy Of Nanostructured Carbon, Timothy Scott Jones

Publicly Accessible Penn Dissertations

Microwave impedance microscopy (MIM) is a scanning probe technique that measures local changes in tip-sample admittance. The imaginary part of the reported change is calibrated with finite element simulations and physical measurements of a standard capacitive sample, and thereafter the output ∆Y is given a reference value in siemens. Simulations also provide a means of extracting sample conductivity and permittivity from admittance, a procedure verified by comparing the estimated permittivity of polytetrafluoroethlyene (PTFE) to the accepted value. Finally, the well-known effective medium approximation of Bruggeman is considered as a means of estimating the volume fractions of the constituents in inhomogeneous ...


Crystal-Amorphous Transformation Via Defect-Templating In Phase-Change Materials, Pavan Nukala Jan 2015

Crystal-Amorphous Transformation Via Defect-Templating In Phase-Change Materials, Pavan Nukala

Publicly Accessible Penn Dissertations

Phase-change materials (PCM) such as GeTe and Ge-Sb-Te alloys are potential candidates for non-volatile memory applications, because they can reversibly and rapidly transform between a crystalline phase and an amorphous phase with medium-range order. Traditionally, crystal-amorphous transformation in these materials has been carried out via melt-quench pathway, where the crystalline phase is heated beyond its melting point by the rising edge of an electric pulse, and the melt phase is quenched by the falling edge into a glassy phase. Formation of an intermediate melt phase in this transformation pathway requires usage of large switching current densities, resulting in energy wastage ...


Engineering Extracellular Matrix Signals Into Fibrous Hyaluronic Acid Hydrogels, Ryan Joseph Wade Jan 2015

Engineering Extracellular Matrix Signals Into Fibrous Hyaluronic Acid Hydrogels, Ryan Joseph Wade

Publicly Accessible Penn Dissertations

Hydrogels have gained widespread use in biomedical applications for their ability to mimic certain features of the natural extracellular matrix (ECM) including tissue-like mechanics, water-swollen environments, and biodegradability. Despite these advantages, hydrogels typically do not present the fibrous architecture of natural ECM, even though this structure can guide cell behavior and tissue function. With this in mind, the overall goal of this dissertation is the translation of hydrogels from hyaluronic acid (HA) macromers into more complex, fibrous networks with spatiotemporal control. First, HA macromers that contain protease-cleavable and fluorescent peptides were synthesized and shown to form both isotropic hydrogels and ...


The Effect Of Cell Contractility And Packing On Extracellular Matrix And Soft Tissue Rheology, Anne Sofieke Geertruide Van Oosten Jan 2015

The Effect Of Cell Contractility And Packing On Extracellular Matrix And Soft Tissue Rheology, Anne Sofieke Geertruide Van Oosten

Publicly Accessible Penn Dissertations

In the past decades it has become clear that the mechanical properties of tissues are important for healthy functioning. The mechanical properties of tissues and their load-bearing components found in the extracellular matrix (ECM) have been tested mechanically to provide more insight. However, there is a discrepancy between tissue and ECM mechanics. In this thesis this discrepancy is investigated with a novel multiaxial rheology method, which addresses a physiologically relevant combination of shear and axial strains. Blood clots are used to study the effect of cell traction and cell packing on ECM mechanics.

The results show that ECM networks compression ...


Non-Specific Interactions Between Cationic Nanoparticle-Polymer Composites And Biomolecules, Matthew Alexander Caporizzo Jan 2014

Non-Specific Interactions Between Cationic Nanoparticle-Polymer Composites And Biomolecules, Matthew Alexander Caporizzo

Publicly Accessible Penn Dissertations

This dissertation describes the consequences of non-specific binding between cationic nanoparticles (NPs) and biological materials ranging from persistence length reduction of single actin filaments, to modified kinetics of myosin V motility, and culminating with correlating THP-1 cell metabolic stress to viscoelastic changes. The bulk of the thesis (chapters 3-5), utilizes optically transparent polymer-NP composites with controllable hierarchical roughness to tune the interaction strength between actin filaments and the surface and impact myosin V kinetics. To generate hierarchical roughness, precise control over the thermodynamics and dynamics of NH2-functionalized NPs in polystyrene-ran-acrylic acid (SAA) is demonstrated in chapter 3. In ...


Flexible Electronics Based On Solution Processable Organic Semiconductors And Colloidal Semiconductor Nanocrystals, Yuming Lai Jan 2014

Flexible Electronics Based On Solution Processable Organic Semiconductors And Colloidal Semiconductor Nanocrystals, Yuming Lai

Publicly Accessible Penn Dissertations

Solution-processable semiconductors hold great potential for the large-area, low-cost fabrication of flexible electronics. Recent advances in flexible electronics have introduced new functional devices such as light-weight displays and conformal sensors. However, key challenges remain to develop flexible devices from emerging materials that use simple fabrication processes and have high-performance.

In this thesis, we first use a solution-processable organic semiconductor to build field-effect transistors on large-area plastic with mobility of 0.1 cm^2/Vs. Combined with passive components, we are able to build voltage amplifiers to capture few mV amplitude bio-signals. This work provides a proof of concept on applying ...


Resistance Switching Devices Based On Amorphous Insulator-Metal Thin Films, Xiang Yang Jan 2014

Resistance Switching Devices Based On Amorphous Insulator-Metal Thin Films, Xiang Yang

Publicly Accessible Penn Dissertations

Nanometallic resistance switching devices based on amorphous insulator-metal thin films are developed to provide a novel non-volatile resistance-switching random-access memory (RRAM) that is CMOS-compatible and meeting technological demand. In these devices, data recording/converting is controlled by a bipolar voltage, which tunes electron localization lengths, hence resistivity, through electron trapping and detrapping. The low-resistance state is a metallic state while the high-resistance state is an insulating state, as established by conductivity studies from 2K to 300K.

The material is exemplified by a Si3N4 thin film with randomly dispersed Pt or Cr. It has been extended to other ...


Designing Nanomaterials For Electronic And Optoelectronic Devices Through Charge Carrier Control, Soong Ju Oh Jan 2014

Designing Nanomaterials For Electronic And Optoelectronic Devices Through Charge Carrier Control, Soong Ju Oh

Publicly Accessible Penn Dissertations

Colloidal semiconductor nanocrystals (NCs) have been shown to be promising materials for electronic and optoelectronic device applications because of their unique size-dependent properties and low-cost solution processability. However, the integration of these materials into devices has been challenging due to a lack of available methods to: 1) accurately control charge carrier statistics, such as majority carrier type and concentration, and carrier mobilities, and 2) efficiently passivate surface defects inherent in NC materials arising from their high surface-volume ratio.

In this thesis, we study the fundamental physics of charge carriers paramount for device application. Then, we introduce several measurement techniques to ...


Injectable Hydrogels For Local Protein Delivery To Engineer Myocardial Remodeling, Brendan Patrick Purcell Jan 2013

Injectable Hydrogels For Local Protein Delivery To Engineer Myocardial Remodeling, Brendan Patrick Purcell

Publicly Accessible Penn Dissertations

The endogenous tissue remodeling events that occur following a myocardial infarction (MI) are inadequate to maintain left ventricular (LV) function, and the progression towards heart failure is often inevitable. Our increased understanding of protein regulators of post MI remodeling provides the opportunity to intervene and engineer tissue remodeling through exogenous protein delivery. The global hypothesis of this dissertation was that the local delivery of therapeutic proteins (SDF-1alpha and TIMP-3) from injectable hyaluronic acid (HA) hydrogels attenuates adverse post MI remodeling processes by providing sustained concentrations of bioactive signals within the remodeling myocardium.

To test this hypothesis, HA based hydrogels were ...


Green Scheduling For Radiant Systems In Buildings, Truong X. Nghiem, Madhur Behl, George J. Pappas, Rahul Mangharam Oct 2012

Green Scheduling For Radiant Systems In Buildings, Truong X. Nghiem, Madhur Behl, George J. Pappas, Rahul Mangharam

Real-Time and Embedded Systems Lab (mLAB)

In this report we look at the problem of peak power reduction for buildings with electric radiant floor heating systems. Uncoordinated operation of a multi-zone radiant floor heating system can result in temporally correlated electricity demand surges or peaks in the building’s electricity consumption. As peak power prices are 200-400 times that of the nominal rate, this uncoordinated activity can result in high electricity costs and expensive system operation. We have previously presented green scheduling as an approach for reducing the aggregate peak power consumption in buildings while ensuring that indoor thermal comfort is always maintained. This report extends ...


Interface Engineering To Control Charge Transport In Colloidal Semiconductor Nanowires And Nanocrystals, David Kiewook Kim Jan 2012

Interface Engineering To Control Charge Transport In Colloidal Semiconductor Nanowires And Nanocrystals, David Kiewook Kim

Publicly Accessible Penn Dissertations

Colloidal semiconductor nanocrystals (NCs) are a class of materials that has rapidly gained prominence and has shown the potential for large area electronics. These materials can be synthesized cheaply and easily made in high quality, with tunable electronic properties. However, evaluating if colloidal nanostructures can be used as a viable semiconducting material for large area electronics and more complex integrated circuits has been a long standing question in the field. When these materials are integrated into solid-state electronics, multiple interfaces need to be carefully considered to control charge transport, these interfaces are the: metal contact/semiconductor, dielectric/semiconductor and the ...


Coordination Of Multirobot Teams And Groups In Constrained Environments: Models, Abstractions, And Control Policies, Nora Ayanian Aug 2011

Coordination Of Multirobot Teams And Groups In Constrained Environments: Models, Abstractions, And Control Policies, Nora Ayanian

Publicly Accessible Penn Dissertations

Robots can augment and even replace humans in dangerous environments, such as search and rescue and reconnaissance missions, yet robots used in these situations are largely tele-operated. In most cases, the robots' performance depends on the operator's ability to control and coordinate the robots, resulting in increased response time and poor situational awareness, and hindering multirobot cooperation.

Many factors impede extended autonomy in these situations, including the unique nature of individual tasks, the number of robots needed, the complexity of coordinating heterogeneous robot teams, and the need to operate safely. These factors can be partly addressed by having many ...