PDMS stamps are pieces of polydimethylsiloxane (PDMS), a silicone, that have been patterned usually against a master mold to form a relief pattern used in soft lithography. This PDMS stamp can be used in either its current form as a relief surface for techniques such as microcontact printing or can also be attached to an external source by tubing so that liquid may be passed through channels on its surface. In this second case it will often be laminated to a surface so that chemistry can be performed on that surface producing a pattern of the PDMS stamp on to the surface. Alternatively a PDMS stamp can be laminated to a second piece of PDMS to form a contained device. It is possible to pattern PDMS with nanometre resolution.
PDMS stamps can be procured from some commercial sources such as Research Micro Stamps. [1]
Many techniques have been developed to modify the basic setups to perform a range of tasks such as assays on small volumes. These kinds of devices are often referred to as microfluidic devices. Because of the small dimensions of these devices flow is laminar, not turbulent, which can lead to many useful properties; however, this reduces the ability of fluid streams to mix.
The main drawback of microcontact printing for biomedical application is that it is not possible to print different molecules with one stamp. To print different (bio)molecules in one step, a new concept is proposed : the macrostamp. [2] It is a stamp composed of dots. The space between the dots corresponds to the space between the wells of a microplate. Then, it is possible to ink, dry and print in one step different molecules.
To apply a homogeneous pressure during the printing step, a magnetic force is used. For that, the stamp is sensitive to a magnetic field by injecting iron powder into a second layer of PDMS. This force can be adjusted for nano and micro-patterns. [3] Fully automated micro contact printing equipment was developed. It consists of the steps of the micro contact printing process : loading, inking, drying, printing, alignment, cleaning, unloading. A pipeting module is used to deposit some drop of liquids like ethanol. [4] This equipment is named InnoSTAMP40. [5]
In computing, a printer is a peripheral machine which makes a durable representation of graphics or text, usually on paper. While most output is human-readable, bar code printers are an example of an expanded use for printers. Different types of printers include 3D printers, inkjet printers, laser printers, and thermal printers.
Photolithography is a process used in the manufacturing of integrated circuits. It involves using light to transfer a pattern onto a substrate, typically a silicon wafer.
A photoresist is a light-sensitive material used in several processes, such as photolithography and photoengraving, to form a patterned coating on a surface. This process is crucial in the electronics industry.
A printed circuit board (PCB), also called printed wiring board (PWB), is a medium used to connect or "wire" components to one another in a circuit. It takes the form of a laminated sandwich structure of conductive and insulating layers: each of the conductive layers is designed with a pattern of traces, planes and other features etched from one or more sheet layers of copper laminated onto or between sheet layers of a non-conductive substrate. Electrical components may be fixed to conductive pads on the outer layers, generally by means of soldering, which both electrically connects and mechanically fastens the components to the board. Another manufacturing process adds vias, drilled holes that allow electrical interconnections between conductive layers.
A microarray is a multiplex lab-on-a-chip. Its purpose is to simultaneously detect the expression of thousands of biological interactions. It is a two-dimensional array on a solid substrate—usually a glass slide or silicon thin-film cell—that assays (tests) large amounts of biological material using high-throughput screening miniaturized, multiplexed and parallel processing and detection methods. The concept and methodology of microarrays was first introduced and illustrated in antibody microarrays by Tse Wen Chang in 1983 in a scientific publication and a series of patents. The "gene chip" industry started to grow significantly after the 1995 Science Magazine article by the Ron Davis and Pat Brown labs at Stanford University. With the establishment of companies, such as Affymetrix, Agilent, Applied Microarrays, Arrayjet, Illumina, and others, the technology of DNA microarrays has become the most sophisticated and the most widely used, while the use of protein, peptide and carbohydrate microarrays is expanding.
A lab-on-a-chip (LOC) is a device that integrates one or several laboratory functions on a single integrated circuit of only millimeters to a few square centimeters to achieve automation and high-throughput screening. LOCs can handle extremely small fluid volumes down to less than pico-liters. Lab-on-a-chip devices are a subset of microelectromechanical systems (MEMS) devices and sometimes called "micro total analysis systems" (μTAS). LOCs may use microfluidics, the physics, manipulation and study of minute amounts of fluids. However, strictly regarded "lab-on-a-chip" indicates generally the scaling of single or multiple lab processes down to chip-format, whereas "μTAS" is dedicated to the integration of the total sequence of lab processes to perform chemical analysis.
Polydimethylsiloxane (PDMS), also known as dimethylpolysiloxane or dimethicone, is a silicone polymer with a wide variety of uses, from cosmetics to industrial lubrication and passive daytime radiative cooling.
In technology, soft lithography is a family of techniques for fabricating or replicating structures using "elastomeric stamps, molds, and conformable photomasks". It is called "soft" because it uses elastomeric materials, most notably PDMS.
Self-assembled monolayers (SAM) of organic molecules are molecular assemblies formed spontaneously on surfaces by adsorption and are organized into more or less large ordered domains. In some cases molecules that form the monolayer do not interact strongly with the substrate. This is the case for instance of the two-dimensional supramolecular networks of e.g. perylenetetracarboxylic dianhydride (PTCDA) on gold or of e.g. porphyrins on highly oriented pyrolitic graphite (HOPG). In other cases the molecules possess a head group that has a strong affinity to the substrate and anchors the molecule to it. Such a SAM consisting of a head group, tail and functional end group is depicted in Figure 1. Common head groups include thiols, silanes, phosphonates, etc.
Nanolithography (NL) is a growing field of techniques within nanotechnology dealing with the engineering of nanometer-scale structures on various materials.
Dip pen nanolithography (DPN) is a scanning probe lithography technique where an atomic force microscope (AFM) tip is used to directly create patterns on a substrate. It can be done on a range of substances with a variety of inks. A common example of this technique is exemplified by the use of alkane thiolates to imprint onto a gold surface. This technique allows surface patterning on scales of under 100 nanometers. DPN is the nanotechnology analog of the dip pen, where the tip of an atomic force microscope cantilever acts as a "pen", which is coated with a chemical compound or mixture acting as an "ink", and put in contact with a substrate, the "paper".
Nanoimprint lithography (NIL) is a method of fabricating nanometer-scale patterns. It is a simple nanolithography process with low cost, high throughput and high resolution. It creates patterns by mechanical deformation of imprint resist and subsequent processes. The imprint resist is typically a monomer or polymer formulation that is cured by heat or UV light during the imprinting. Adhesion between the resist and the template is controlled to allow proper release.
Microfabrication is the process of fabricating miniature structures of micrometre scales and smaller. Historically, the earliest microfabrication processes were used for integrated circuit fabrication, also known as "semiconductor manufacturing" or "semiconductor device fabrication". In the last two decades, microelectromechanical systems (MEMS), microsystems, micromachines and their subfields have re-used, adapted or extended microfabrication methods. These subfields include microfluidics/lab-on-a-chip, optical MEMS, RF MEMS, PowerMEMS, BioMEMS and their extension into nanoscale. The production of flat-panel displays and solar cells also uses similar techniques.
Microcontact printing is a form of soft lithography that uses the relief patterns on a master polydimethylsiloxane (PDMS) stamp or Urethane rubber micro stamp to form patterns of self-assembled monolayers (SAMs) of ink on the surface of a substrate through conformal contact as in the case of nanotransfer printing (nTP). Its applications are wide-ranging including microelectronics, surface chemistry and cell biology.
Printed electronics is a set of printing methods used to create electrical devices on various substrates. Printing typically uses common printing equipment suitable for defining patterns on material, such as screen printing, flexography, gravure, offset lithography, and inkjet. By electronic-industry standards, these are low-cost processes. Electrically functional electronic or optical inks are deposited on the substrate, creating active or passive devices, such as thin film transistors; capacitors; coils; resistors. Some researchers expect printed electronics to facilitate widespread, very low-cost, low-performance electronics for applications such as flexible displays, smart labels, decorative and animated posters, and active clothing that do not require high performance.
Smart Label, also called Smart Tag, is an extremely flat configured transponder under a conventional print-coded label, which includes chip, antenna and bonding wires as a so-called inlay. The labels, made of paper, fabric or plastics, are prepared as a paper roll with the inlays laminated between the rolled carrier and the label media for use in specially-designed printer units.
Bio-MEMS is an abbreviation for biomedical microelectromechanical systems. Bio-MEMS have considerable overlap, and is sometimes considered synonymous, with lab-on-a-chip (LOC) and micro total analysis systems (μTAS). Bio-MEMS is typically more focused on mechanical parts and microfabrication technologies made suitable for biological applications. On the other hand, lab-on-a-chip is concerned with miniaturization and integration of laboratory processes and experiments into single chips. In this definition, lab-on-a-chip devices do not strictly have biological applications, although most do or are amenable to be adapted for biological purposes. Similarly, micro total analysis systems may not have biological applications in mind, and are usually dedicated to chemical analysis. A broad definition for bio-MEMS can be used to refer to the science and technology of operating at the microscale for biological and biomedical applications, which may or may not include any electronic or mechanical functions. The interdisciplinary nature of bio-MEMS combines material sciences, clinical sciences, medicine, surgery, electrical engineering, mechanical engineering, optical engineering, chemical engineering, and biomedical engineering. Some of its major applications include genomics, proteomics, molecular diagnostics, point-of-care diagnostics, tissue engineering, single cell analysis and implantable microdevices.
Perfluorodecyltrichlorosilane, also known as FDTS, is a colorless liquid chemical with molecular formula C10H4Cl3F17Si. FDTS molecules form self-assembled monolayers. They form covalent silicon–oxygen bonds to free hydroxyl (–OH) groups, such as the surfaces of glass, ceramics, or silica.
Directed assembly of micro- and nano-structures are methods of mass-producing micro to nano devices and materials. Directed assembly allows the accurate control of assembly of micro and nano particles to form even the most intricate and highly functional devices or materials.
Three-dimensional (3D) microfabrication refers to manufacturing techniques that involve the layering of materials to produce a three-dimensional structure at a microscopic scale. These structures are usually on the scale of micrometers and are popular in microelectronics and microelectromechanical systems.