Selected Publications using SonoPlot's Microplotter Systems
Programmable on-chip DNA compartments as artificial cells
Eyal Karzbrun,(1) Alexandra M. Tayar,(1) Vincent Noireaux,(2) Roy H. Bar-Ziv(1).
Department of Materials and Interfaces, Weizmann Institute of Science, (2) Department of Physics, University of Minnesota
The assembly of artificial cells capable of executing synthetic DNA programs has been an important goal for basic research and biotechnology. We assembled two-dimensional DNA compartments fabricated in silicon as artificial cells capable of metabolism, programmable protein synthesis, and communication. Metabolism is maintained by continuous diffusion of nutrients and products through a thin capillary, connecting protein synthesis in the DNA compartment with the environment. We programmed protein expression cycles, autoregulated protein levels, and a signaling expression gradient, equivalent to a morphogen, in an array of interconnected compartments at the scale of an embryo. Gene expression in the DNA compartment reveals a rich, dynamic system that is controlled by geometry, offering a means for studying biological networks outside a living cell.
Solution Processable Transistors and Switches: Plotter Printing and Spray Deposition of Materials
Petro Lutsyk, Marcin Sojka, Krzysztof Janu, Juliusz Sworakowski.
Wroclaw University of Technology (2014).
Organic electronic devices, like field-effect transistors (FETs) or switches, have received extensive attention because of their potential application in flexible electronics, large-area displays, radio-frequency identification tags (RFIDs), sensors, etc. Crucial advantage of organic electronics rests in a prospect of low cost manufacturing of electronic circuits achievable by deposition of electronic components from solution by, e.g, ink-jet printing and spray coating. The printing is desirable in the case of fine structures like interdigitated electrodes while spray brushing is more effective for fabrication of large area thin films.
A common challenge in most printing techniques is the limitation in feature size. The line width of 20-100 um is achievable with standard ink-jet printers. The size of printed features may be decreased down to a few microns using laster-assisted technique at the price, however, of a dramatic increase of the cost of fabrication. One of the ways of obtaining small-size features of printed elements may be paved by plotter printing. Advantage of the plotting technique is possibility of drawing very smooth lines enabling one to achieve short (ca 5 um) channel between source and drain electrodes.
Microstructured Silicone Substrate for Printable and Stretchable Metallic Films
Adam P. Robinson, Ivan Minev, Ingrid M. Graz, and Stephanie P. Lacour.
Nanoscience Centre, Department of Engineering, University of Cambridge (2011).
Stretchable electronics (i.e., hybrid inorganic or organic circuits integrated on elastomeric substrates) rely on elastic wiring. We present a technique for fabricating reversibly stretchable metallic films by printing silver-based ink onto microstructured silicone substrates. The wetting and pinning of the ink on the elastomer surface is adjusted and optimized by varying the geometry of micropillar arrays patterned on the silicone substrate. The resulting films exhibit high electrical conductivity (!11 000 S/cm) and can stretch reversibly to 20% strain over 1000 times without failing electrically. The stretchability of the g200 nm thick metallic !lm relies on engineered strain relief in the printed !lm on patterned PDMS.
Ink-plotting of YBa2Cu3O7-x- filamented structures
A.Kirchner(1), R. Hühne(1), I. Birlik(1), P. Vermeir, (2) I. Van Driessche (2), L. Schultz1, B. Holzapfel(1). (1)IFW Dresden, Institute for Metallic Materials, (2)Dep. Inorganic and Physical Chemistry, Ghent University (2011).
Chemical Solution Deposition (CSD) is a promising process for industrial long length production of high temperature superconducting tapes because of its low-cost, high-speed production and good scalability. YBa2Cu3O7-x (YBCO) coated conductors are the favourable material with excellent superconducting properties including sufficient high Jc-performance. Nevertheless, the alternating current (ac)-losses are still too high for applications of wires in motors. A special plotting technique allows a printing of filamented structures of YBCO thin layers. The hysteresis losses in such striped films are much lower than in continuously coated substrates with a homogeneous YBCO layer.
Lines as well as rectangular shaped YBCO-structures were deposited by an ink plotting system on single crystal substrates. Different inks were tested, among them an environmentally friendly, water-based fluorine-free YBCO precursor solution as well as an ink, synthesised according to the TFA route.
A High Throughput, High Resolution Enzymatic Lithography Process: Effect of Crystallite Size, Moisture and Enzyme Concentration
Zhantong Mao; Manoj Ganesh; Michael Bucaro; Igor Smolianski; Richard A. Gross; Alan M. Lyons. Department of Chemistry, College of Staten Island, City University of New York, Department of Chemistry and Biology, Rensselaer Polytechnic Institute, SyntheZyme LLC (2014).
By bringing enzymes into contact with predefined regions of a surface, a polymer film can be selectively degraded to form desired patterns that find a variety of applications in biotechnology and electronics. This so-called "enzymatic lithography" is an environmentally friendly process as it does not require actinic radiation or synthetic chemicals to develop the patterns. A significant challenge to using enzymatic lithography has been the need to restrict the mobility of the enzyme in order to maintain control of feature sizes. Previous approaches have resulted in low throughput and were limited to polymer films only a few nanometers thick. In this paper, we demonstrate an enzymatic lithography system based on Candida antartica lipase B (CALB) and poly(ε-caprolactone) (PCL) that can resolve fine-scale features, (<1 μm across) in thick (0.1-2.0 μm) polymer films. A Polymer Pen Lithography (PPL) tool was developed to deposit an aqueous solution of CALB onto a spin-cast PCL film. Immobilization of the enzyme on the polymer surface was monitored using fluorescence microscopy by labeling CALB with FITC. The crystallite size in the PCL films was systematically varied; small crystallites resulted in significantly faster etch rates (20 nm/min) and the ability to resolve smaller features (as fine as 1 μm). The effect of printing conditions and relative humidity during incubation is also presented. Patterns formed in the PCL film were transferred to an underlying copper foil demonstrating a "Green" approach to the fabrication of printed circuit boards.
Patterned Enzymatic Degradation of Poly(ε-caprolactone) by High- Affinity Microcontact Printing and Polymer Pen Lithography
Manoj Ganesh, Jonathan Nachman, Zhantong Mao, Alan Lyons, Miriam Rafailovich, and Richard Gross. Polytechnic Institute of NYU, State University of New York at Stony Brook, College of Staten Island (CUNY) (2013).
This paper reports deposition of Candida antarctica Lipase B (CALB) on relatively thick poly(ε-caprolactone) (PCL) films (300−500 nm) to create well-defined patterns using two different writing techniques: high-affinity microcontact (HA-μCL) and polymer pen (PPL) lithography. For both, an aqueous CALB ink is absorbed onto a polydimethylsiloxane (PDMS) writing implement (PDMS stamp or a PDMS pen tip), which is transferred to a spun-cast PCL film. HA-μCL experiments demonstrated the importance of applied pressure to obtain high-resolution patterns since uniform contact is needed between raised 20 μm parallel line regions of the PDMS stamp and the surface. AFM imaging shows pattern formation evolves gradually over incubation time only in areas stamped with CALB cutting through spherulites without apparent influence by grain boundaries. Strong binding of CALB to PCL is postulated as the mechanism by which lateral diffusion is limited. PPL enables formation of an arbitrary image by appropriate programming of the robot. The PDMS pen tips were coated with an aqueous CALB solution and then brought into contact with the PCL film to transfer CALB onto the surface. By repeating the ink transfer step multiple times where pen tips are brought into contact with the PCL film at a different locations, a pattern of dots is formed. After printing, patterns were developed at 37 °C and 95% RH. Over a 7-day period, CALB progressively etched the PCL down to the silicon wafer on which it was spun (350 nm) giving round holes with diameters about 10 μm. AFM images show the formation of steep PCL walls indicating CALB degraded the PCL film in areas to which it was applied. This work demonstrates that high-resolution patterns can be achieved without immobilizing the enzyme on the surface of polymeric stamps that limits the depth of features obtained as well as the throughput of the process.
Fully Printed Separated Carbon Nanotube Thin Film Transistor Circuits and Its Application in Organic Light Emitting Diode Control
Pochiang Chen,† Yue Fu,‡ Radnoosh Aminirad,†,§ Chuan Wang,‡ Jialu Zhang,‡ Kang Wang,§ Kosmas Galatsis,*,†,§ and Chongwu Zhou.†Aneeve Nanotechnologies LLC, ‡Department of Electrical Engineering, University of Southern California, §Department of Electrical Engineering, University of California at Los Angeles (2011).
The advantages of printed electronics and semi-conducting single-walled carbon nanotubes (SWCNTs) are combined for the #rst time for display electronics. Conductive silver ink and 98% semiconductive SWCNT solutions are used to print back-gated thin #lm transistors with high mobility, high on/off ratio, and high current carrying capacity. In addition, with printed polyethylenimine with LiClO4 as the gating material, fully printed top-gated devices have been made to work as excellent current switches for organic light emitting diodes (OLEDs). An OLED driving circuit composed of two top-gated fully printed transistors has been fabricated, and the successful control over external OLED is demonstrated. Our work demonstrates the signi#cant potential of using printed carbon nanotube electronics for display backplane applications.
Glycocalyx remodeling with proteoglycan mimetics promotes neural specification in embryonic stem cells.
Mia L. Huang, Raymond A. A. Smith, Greg W. Trieger, and Kamil Godula. Department of Chemistry and Biochemistry, University of California, San Diego, California 92093-0358, United States (2014).
Growth factor (GF) signaling is a key determinant of stem cell fate. Interactions of GFs with their receptors are often mediated by heparan sulfate proteoglycans (HSPGs). Here, we report a cell surface engineering strategy that exploits the function of HSPGs to promote differentiation in embryonic stem cells (ESCs). We have generated synthetic neoproteoglycans (neoPGs) with affinity for the fibroblast growth factor 2 (FGF2) and introduced them into plasma membranes of ESCs deficient in HS biosynthesis. There, the neoPGs assumed the function of native HSPGs, rescued FGF2-mediated kinase activity, and promoted neural specification. This glycocalyx remodeling strategy is versatile and may be applicable to other types of differentiation.
Cold-plasma modification of oxide surfaces for covalent biomolecule attachment.
B. J. Larson, J. M. Helgren, S. O. Manolache, A. Y. Lau, M. G. Lagally, and F. S. Denes. Biosensors and Bioelectronics 21, 796-801 (2005).
While many processes have been developed to modify the surface of glass and other oxides for biomolecule attachment, they rely primarily upon wet chemistry and are costly and time-consuming. We describe a process that uses a cold plasma and a subsequent in vacuo vapor-phase reaction to terminate a variety of oxide surfaces with epoxide chemical groups. These epoxide groups can react with amine-containing biomolecules, such as proteins and modified oligonucleotides, to form strong covalent linkages between the biomolecules and the treated surface. The use of a plasma activation step followed by an in vacuo vapor-phase reaction allows for the precise control of surface functional groups, rather than the mixture of functionalities normally produced. By maintaining the samples under vacuum throughout the process, adsorption of contaminants is effectively eliminated. This process modifies a range of different oxide surfaces, is fast, consumes a minimal amount of reagents, and produces attachment densities for bound biomolecules that are comparable to or better than commercially available
Polymer light emitting diodes and poly(di-n-octylfluorene) thin films as fabricated with a microfluidics applicator.
H. Cheun, P. P. Rugheimer, B. J. Larson, P. Gopalan, M. G. Lagally, and M. J. Winokur. Journal of Applied Physics 100, 073510 (2006).
A microfluidics applicator is used in the fabrication of a polyfluorene based polymer light emitting diode (PLED). This procedure results in a single contiguous polymer trace and, as a consequence of the high deposition speed, shows unusual characteristics in both the film morphology and polymer microstructure. These aspects are studied using fluorescence microscopy, profilometry, and optical absorption and emission pectroscopies. Room temperature analysis of the poly (di-n-octylfluorene) indicates that the combination of high-speed deposition and rapid drying process traps the polymer into a metastable conformational state. Optical spectroscopy at reduced temperature identifies emission from at least two distinct conformational chromophores. At elevated temperature there is an abrupt, irreversible transition to a more conventional structural form. Electroluminesence data from PLED test devices are shown and this demonstrates some of the unique opportunities afforded by this method of polymer film formation and device fabrication. Device operation is not optimized.
Controlled deposition of picoliter amounts of fluid using an ultrasonically driven micropipette.
B.J. Larson, S.D. Gillmor, and M.G. Lagally. Review of Scientific Instruments 75, 832-836 (2004).
A fluid microplotter that uses ultrasonics to deposit small fluid features has been constructed. It consists of a dispenser, composed of a micropipette fastened to a piece of lead zirconate titanate piezoelectric, attached to a precision positioning system. When an electrical signal of the appropriate frequency and voltage is applied, solution in the tip of the micropipette wicks to the surface in a controlled fashion. The gentle pumping of fluid to the surface occurs when the micropipette is driven at frequencies in the range of 400 - 700 kHz. Spots with diameters smaller than several microns can be deposited in this manner. Continuous lines can also be produced. Several examples of deposited patterns and structures are described. This means of deposition represents a higher-resolution alternative to standard fluid deposition techniques in the fabrication of biological microarrays or polymer-based circuits.
New technologies for fabricating biological microarrays
B. J. Larson. Ph.D. thesis, University of Wisconsin-Madison (2005).
Microarrays, composed of thousands of spots of different biomolecules attached to a solid substrate, have emerged as one of the most important tools in modern biological research. This dissertation contains the description of two technologies that we have developed to reduce the cost and improve the quality of spotted microarrays.
The first is a device, called a fluid microplotter, that uses ultrasonics to deposit spots with diameters of less than 5 microns. It consists of a dispenser, composed of a micropipette fastened to a piece of PZT piezoelectric, attached to a precision positioning system. A gentle pumping of fluid to the surface occurs when the micropipette is driven at specific frequencies. Spots or continuous lines can be deposited in this manner. The small fluid features conserve expensive and limited-quantity biological reagents. Additionally, the spots produced by the microplotter can be very regular, with coefficients of variability for their diameters of less than 5%.
We characterize the performance of the microplotter in depositing fluid and examine the theoretical underpinnings of its operation. We present an analytical expression for the diameter of a deposited spot as a function of droplet volume and wettability of a surface and compare it with experimental results. We also examine the resonant properties of the piezoelectric element used to drive the dispenser and relate that to the frequencies at which pumping occurs. Finally, we propose a mechanism to explain the pumping behavior within the microplotter dispenser.
The second technology we present is a process that uses a cold plasma and a subsequent in vacuo vapor-phase reaction to terminate a variety of oxide surfaces with epoxide chemical groups. These epoxide groups can react with amine-containing biomolecules, such as proteins and modified oligonucleotides, to form strong covalent linkages between the biomolecules and the treated surface. The use of a plasma activation step followed by an in vacuo vapor-phase reaction allows for the precise control of surface functional groups, rather than the mixture of functionalities normally produced. By maintaining the samples under vacuum throughout the process, adsorption of contaminants is effectively eliminated. This process modifies a range of different oxide surfaces, is fast, consumes a minimal amount of reagents, and produces attachment densities for bound biomolecules that are comparable to or better than commercially available substrates.
We show applications of these two technologies in the fabrication of protein microarrays, enhancement of MALDI mass spectrometry, deposition of polymer electronics, directed growth of carbon nanotubes, and the chemical modification of carbon-containing materials.