Μm Edge Length Research Articles

Fluorescence Multi-Detection Device Using a Lensless Matrix Addressable microLED Array.

A Point-of-Care system for molecular diagnosis (PoC-MD) is described, combining GaN and CMOS chips. The device is a micro-system for fluorescence measurements, capable of analyzing both intensity and lifetime. It consists of a hybrid micro-structure based on a 32 × 32 matrix addressable GaN microLED array, with square LEDs of 50 µm edge length and 100 µm pitch, with an underneath wire bonded custom chip integrating their drivers and placed face-to-face to an array of 16 × 16 single-photon avalanche diodes (SPADs) CMOS. This approach replaces instrumentation based on lasers, bulky optical components, and discrete electronics with a full hybrid micro-system, enabling measurements on 32 × 32 spots. The reported system is suitable for long lifetime (>10 ns) fluorophores with a limit of detection ~1/4 µM. Proof-of-concept measurements of streptavidin conjugate Qdot™ 605 and Amino PEG Qdot™ 705 are demonstrated, along with the device ability to detect both fluorophores in the same measurement.

Local fluctuation of the relative density of glass powders over the entire viscous sintering process

Using high-resolution X-ray computed tomography and 3D image analysis, the global relative density was determined and fluctuations in relative density were localized and quantified in a series of sintered glass bodies made of 80 μm glass spheres over the entire sintering process. A representative volume element (RVE) in the sintered body was divided into cubic volumes of 500, 250 and 125 µm edge length by an automatic segmentation routine. It was found that the expected decrease in coarseness C from the initial to the final sintering stage is interrupted by an intermediate stage with highest C and a characteristic bimodal density distribution. The bimodality of the intermediate stage is due to spatially separated denser arrangements within the RVE with closed pores and less dense arrangements with a network of interconnected or open pores. The spatial heterogeneity is biased in the z-direction due to friction caused by adhesion with the substrate.

Excellent microwave absorption of void@carbon@TiO2 cubes by a template sol method

The ingenious design of heterogeneous structures is an effective strategy for developing advanced microwave absorption materials. In this study, high-efficiency void@carbon@TiO2 (void@C@TiO2) cubes were synthesized by a template sol method. Compared with void@carbon (void@C) and void@TiO2 cubes, the void@C@TiO2 cubes/paraffin composites of 2.1 µm edge length show excellent microwave absorption performances (MAPs). When the thickness is 2.1 mm, the minimum reflection loss (RL) of – 69.8 dB is superior to – 31.5 dB of void@C cubes at 4.1 mm and – 3.1 dB of void@TiO2 cubes at 3.7 mm. The effective absorption frequency covers 11.8 GHz (6.2–18.0 GHz, RL below – 10 dB) by matching the coating thickness with 1.7–5.0 mm. The enhanced MAPs originated from the synergistic processes of good impedance matching (|Zin/Z0|) and various microwave dissipation mechanisms, including electrical conduction, interfacial charge accumulation, and defect dipolar polarization. The void@C@TiO2 cubes are a lightweight, easy, environment-friendly, and extendible strategy for microwave absorption applications.

Laser-induced forward transfer as a potential alternative to pick-and-place technology when assembling semiconductor components

Fabrication technologies for the semiconductor industry have enabled ever smaller electronic components but now face a fundamental limit in their assembly. As the components get smaller and smaller, the difficulty of assembly increases. At the same time, the number of components per circuit board area is growing, as is the case with LED displays. This in turn calls for an increasing assembly rate. The conventional pick-and-place method can handle approximately 25–30 thousand dies per hour but has increasing limitations when component dimensions are reduced below 150 μm edge length. Laser-induced forward transfer is used as a potential alternative for an assembly of semiconductor components. This technique allows to transfer semiconductor components with an edge length of less than 150 μm to a target substrate. The current process is contactless, damage-free, and has sufficient placement accuracy. If this process is combined with the property of high-pulse repetition rates, it is possible to significantly increase the assembly rate of semiconductor components compared to the current limitations. The aim of this study is to characterize the flight properties of silicon semiconductor components of various dimensions in a laser-driven transfer process using optical imaging methods. This method allows to analyze velocity, the direction of fall, and acceleration of falling components. The results can be used to analyze the transfer behavior of various component sizes and to make estimates of the stability of the transfer process.

Rapid Prototyping of Moulds for PDMS-based Microfluidic Chips

Abstract To shorten the production time for PDMS-moulds by additive manufacturing (AM) several 3D printers have been investigated in comparison to standard micro-milling by producing benchmark structures. These are evaluated regarding their shape accuracy, the transparency of the casted PDMS which is linked to the surface quality of the mould, and the production time until the moulds are ready to use. Even though the additively manufactured moulds showed significantly better surface quality and shorter production time, the necessary shape accuracy for non-square-structures or structures with < 250 μm edge length could not be achieved due to limiting factors like nozzle diameter, size of the digital micromirror device or spot size of the LCD-panel.

Implementation of a High-Repetition-Rate Laser in an AP-SMALDI MSI System for Enhanced Measurement Performance.

Matrix-assisted laser desorption/ionization mass spectrometry imaging is a promising tool in the life sciences for obtaining spatial and chemical information from complex biological samples. State-of-the-art setups combine high mass resolution and high mass accuracy with high lateral resolution, offering untargeted insights into biochemical processes on the single-cell length scale. Despite recent technological breakthroughs, the sensitivity and acquisition speed of many setups are often in competition with achievable pixel resolutions below 25 μm. New measurement modes were developed by implementing a high-repetition-rate laser into an AP-SMALDI10 ion source, coupled to an orbital trapping mass spectrometer. These new MSI modes allow for a modular use of the new setup. We demonstrate that the system allows single cell features to be visualized in mouse brain tissue sections at a pixel resolution of 5 μm and an imaging speed of 18 pixels/s. Furthermore, the analytical sensitivity was improved in another measurement mode by applying multiple pulses of a highly focused laser beam over larger square pixels ≥25 μm edge length, increasing ion signal intensities up to 20-fold on tissue and decreasing the limit of detection by 1 order of magnitude.

Stress and Deformation Analysis of Piezoresistive Square Diaphragm Nano Pressure Sensor

Pressure sensors are among the most widely used MEMS product as sensors in commercial and industrial applications. The diaphragm structure, thickness, and dimensions along with the placement, size, and shape of the piezo resistors are important in the process of designing a pressure sensor. This paper presents the design and simulation of the square diaphragm to analysis the deformation and stress of various materials as well as for the different thickness of the diaphragms at low pressure in the range of 0.1 to 1.5 bar. The design of diaphragm is as a 10 μm thick square diaphragm with 800 μm edge length are considered, which were analyzed by using ANSYS 17 software. The results show that deformation and stress reduction as in the increase in the thickness, which is directly related to the performance of the diaphragm. CNT based diaphragm also showed the improved performance of the pressure sensor as compared to the silicon and polysilicon material.

1-nm-Wide Hydrated Dipole Arrays Regulate AuNW Assembly on Striped Monolayers in Nonpolar Solvent

Summary We show that striped phases of horizontally oriented phospholipids presenting 1-nm-wide orientable dipole arrays can order and straighten flexible 2-nm-diameter gold nanowires (AuNWs) with lengths (up to 1 μm) that greatly exceed the template pitch (∼7.5 nm). AuNW ordering can extend over areas > 100 μm2. Whereas wires bundle in solution, with contact between ligand shells, wires adsorbing to the template separate to much larger center-to-center distances (e.g., 12–30 nm) near multiples of the template pitch, consistent with repulsive interactions between wires emerging during interactions with dipole arrays in the template. AuNW assembly was carried out in cyclohexane, a nonpolar solvent. Interestingly, we found that wire ordering was contingent on the extent of phospholipid headgroup hydration and the presence of excess oleylamine, which assembled into hemicylindrical micelles around the hydrated headgroups. Together, these components generated a protected polar environment that enabled the phospholipid headgroups to function collectively to regulate AuNW assembly.

A demonstrator for a flexible active microelectrode array with high electrode number

Abstract The integration of dies is a possibility to reduce the number of conducting tracks within electrical active implants. For passive microelectrode arrays the number of conducting tracks limits the number of electrodes. By embedding an array of small dies (250 μm edge length) employed to amplify and multiplex the signals of 25 electrodes each into a flexible foil we create a flexible active microelectrode array with more than 1000 electrodes. A fabrication process was developed containing a transfer process for the dies as well as an embedding procedure. Here a non-functional Dummy-System is presented as a demonstrator proving the feasibility of the proposed microelectrode array.

Density-Gradient Control over Nanoparticle Supercrystal Formation.

With the advent of DNA-directed methods to form "single crystal" nanoparticle superlattices, new opportunities for studying the properties of such structures across many length scales now exist. These structure-property relationships rely on the ability of one to deliberately use DNA to control crystal symmetry, lattice parameter, and microscale crystal habit. Although DNA-programmed colloidal crystals consistently form thermodynamically favored crystal habits with a well-defined symmetry and lattice parameter based upon well-established design rules, the sizes of such crystals often vary substantially. For many applications, especially those pertaining to optics, each crystal can represent a single device, and therefore size variability can significantly reduce their scope of use. Consequently, we developed a new method based upon the density difference between two layers of solvents to control nanoparticle superlattice formation and growth. In a top aqueous layer, the assembling particles form a less viscous and less dense state, but once the particles assemble into well-defined rhombic dodecahedral superlattices of a critical size, they sediment into a higher density and higher viscosity sublayer that does not contain particles (aqueous polysaccharide), thereby arresting growth. As a proof-of-concept, this method was used to prepare a uniform batch of Au nanoparticle (20.0 ± 1.6 nm in diameter) superlattices in the form of 0.95 ± 0.20 μm edge length rhombic dodecahedra with body-centered cubic crystal symmetries and a 49 nm lattice parameter (cf. 1.04 ± 0.38 μm without the sublayer). This approach to controlling and arresting superlattice growth yields structures with a 3-fold enhancement in the polydispersity index.

Stereolithographic Additive Manufacturing of Solid Electrolyte Ceramic Sheets with Micro Emboss Pattern for All Solid Battery Application

Additive manufacturing (AM) and 3 dimensional printing (3DP) technologies have been developed to create metal or ceramic components with complicated structures rapidly and exactly by computer aided design, manufacture and evaluation (CAD/CAM/CAE). In a stereolithographic AM technique, photo sensitive acrylic resin with nanoparticles of ceramics or metals spreading equally is used. The resins are spread on a glass substrate at certain thickness, and ultraviolet laser beams are scanned to form and laminate cross sectional layers through photo chemical reactions. Micro functional structures could be created through conventional dewaxing and sintering processes. The stereolithography had been customized to process ceramic components with functional structures of geometric patterns, for example, electromagnetic devices, biological implants and energy storage modules, which are centimeter order components including micrometer sized structures.In this investigation, micro emboss patterns composed of solid electrolyte Li7La3Zr2O12 (LLZ) for longer service life, higher efficiency and improved safety of all solid battery. In generic battery, fluid material is used as an electrolyte, and it is an obstacle to improve performance of the battery. Then, all solid battery is an innovative form of battery.The solid electrolyte LLZ particles of 1 μm in average diameter were dispersed into a photo sensitive acrylic resin at 25 volume %. The schematic illustrated stereolithography process was shown in Fig. 1. The obtained paste was spread with 10 μm layer thickness on a glass substrate by using a mechanical knife edge. A laser beam of 355 nm in wavelength was scanned to laminate cross sectional layers at 1200 mm/s in drawing speed. The laser power was changed from 8 to200 mW, and the beam diameter was changed from 10 to 50 μm.The micro emboss pattern of 10×10×0.2 mm in outer dimensions with angle holes of 240×240×100 μm in sizes on the upper surface was designed as shown in Fig. 2. Through the stereolithographic AM, solid cross sections of 10 μm in thickness were formed and laminated for 20 layers. The lower part of 20 layers was a simple plate, and the upper part had an emboss pattern. The laser lithographic conditions of scanning speed, irradiation power, spot size, raster pattern and offset are shown in Tab. 1. The meanings of these parameters were schematically illustrated in Fig. 3 and Fig. 4. The fabricated emboss patterns were observed by using a digital optical microscope to measure the part accuracy.In the lithography process, the laser beam should be scattered by the dispersed particles, the photo sensitive resin were over cured comparing with the laser beam diameter. To increase the dimensional accuracies in the cross sectional micro patterns, the scanning lines of the laser beam were adjusted about 10–15 μm in offset values according to the drawing conditions as shown in Table 1 and Fig. 3-(b). The scan pattern X/Y means a single laser scanning for X and Y-directions on odd and even numbered layers, respectively as shown in Fig. 4. The acryl micro emboss structures with LLZ particles dispersion are shown in Fig. 5 (a), (b) and (c) using lithographic conditions of A, B and C in Table 1, respectively.As shown in Fig. 5-(a), the anisotropic angle holes of 150×200 μm in edge lengths were obtained through the highest laser power drawing. Comparing with this, in the case of Fig. 5-(b), the isotropic angle holes of 260 μm in edge length were opened in the composite plate with the larger size toward the graphically designed model as shown in Fig. 2. Through the optimization of lithographic conditions, the laser power and edge offset were decided, and the micro emboss pattern with higher part accuracy could be obtained as shown in Fig. 5-(c). The size tolerance was less than 10 μm. Each layer could be joined strongly without cracking. Figure 6-(a) and (b) are the composite precursor and full ceramic component through the conventional dewaxing and sintering, respectively. The solid electrolyte particles of lithium-lanthanam-titanate (LLT: Li0.33La0.55TiO3) were dispersed into acrylic resin at 38 volume %. The micro emboss pattern could be obtained according to the design model.By using stereolithographic additive manufacturing, micro acryl components with solid electrolyte particles of Li7La3Zr2O12 (LLZ) could be fabricated. Micro emboss structures composed of fine angle holes were created to be applied for all solid battery through computer aided design, manufacture and evaluation. Part accuracies were improved successfully by optimization of laser lithographic conditions. Composite precursors could be dewaxed and sintered into full ceramic components.

Chemical vapor deposition growth of large-scale hexagonal boron nitride with controllable orientation

Chemical vapor deposition (CVD) synthesis of large-domain hexagonal boron nitride (h-BN) with a uniform thickness is very challenging, mainly due to the extremely high nucleation density of this material. Herein, we report the successful growth of wafer-scale, high-quality h-BN monolayer films that have large single-crystalline domain sizes, up to ~72 µm in edge length, prepared using a folded Cu-foil enclosure. The highly confined growth space and the smooth Cu surface inside the enclosure effectively reduced the precursor feeding rate together and induced a drastic decrease in the nucleation density. The orientation of the as-grown h-BN monolayer was found to be strongly correlated to the crystallographic orientation of the Cu substrate: the Cu (111) face being the best substrate for growing aligned h-BN domains and even single-crystalline monolayers. This is consistent with our density functional theory calculations. The present study offers a practical pathway for growing high-quality h-BN films by deepening our fundamental understanding of the process of their growth by CVD.

Increasing the aperture of x-ray mosaic lenses by freeze drying

Point focus x-ray mosaic lenses are limited in aperture by the aspect ratio that can be reached in the micro fabrication process. In lithography based micro fabrication processes, which are used to fabricate the lens pillar structures, the achievable aspect ratio is restricted by structure collapse due to capillary forces which occur during drying after development. Capillary forces can be avoided by freeze drying, hence avoiding the direct phase change from liquid to gas. Substituting conventional drying by freeze drying using cyclohexane at a temperature of −10 °C, we could increase the achievable aspect ratio for the triangular pillar structures with edge length of 10 to 45 µm of the x-ray mosaic lenses by up to a factor of 2.2 with no further changes in process, material or structural geometry. A maximum aspect ratio of 30 was achieved for pillars with 10 µm edge length. The process can readily be employed to other structures or lithography techniques.

Effect of piezoresistor configuration on output characteristics of piezoresistive pressure sensor: an experimental study

Piezoresistive sensing is one of the most frequently used transduction mechanism in pressure sensors. The piezoresistor placement on the diaphragm and the piezoresistor configuration play a pivotal role in determining the output characteristics of a pressure sensor. In this work, two different pressure sensors with different transverse piezoresistor configurations are studied to determine the effect of piezoresistor configuration on the sensitivity and non-linearity of the pressure sensors. A sensor structure with a square diaphragm size of 1,480 µm edge length and diaphragm thickness of 50 µm is chosen for the study. The design considerations for piezoresistor placement and the piezoresistor shapes are discussed in detail. The sensors are fabricated with bulk micromachined diaphragm and polysilicon piezoresistors. The sensor characteristics are determined for three temperatures, namely, ?5, 25 and 55 °C and for a pressure range of 0---30 Bar. The characterization results indicate that the design with two piezoresistor arms in transverse piezoresistor configuration (2 × 2 Design) has higher sensitivity than the single arm configuration (2 × 1 Design) by about 25 % at 25 °C but it also has a higher non-linearity. The study shows the importance of selecting the proper piezoresistor configuration in the design of pressure sensors.

Effect of specific surface microstructures on substrate endothelialisation and thrombogenicity: Importance for stent design.

In coronary artery disease, highly stenosed arteries are frequently treated by stent implantation, which thereafter necessitates a dual-antiplatelet therapy (DAPT) in order to prevent stent-thrombosis. We hypothesized that specific patterns of microstructures on stents can accelerate endothelialisation thereby reducing their thrombogenicity and the DAPT duration. Differently designed, 2-5 μm high elevations or hollows were lithographically etched on silicon plates, subsequently coated with silicon carbide. Smooth silicon plates and bare metal substrates were used as controls. To assess attachment and growth of human umbilical vein endothelial cells under static or flow conditions, actin cytoskeleton was visualised with green phalloidin. Endothelial migration was assessed in a modified barrier assay. To investigate surface thrombogenicity, platelets were incubated on the structured surfaces in static and flow conditions, and visualised with fluorescein-conjugated P-selectin antibody. Images were taken with incident-light fluorescent microscope for non-transparent objects. Compared to smooth surface, flat cubic elevations (5 μm edge length) improved endothelial cell attachment and growth under static and dynamic conditions, whereas smaller, spiky structures (2 μm edge length) had a negative influence on endothelialisation. Endothelial cell migration was fastest on flat cubic elevations, hollows, and smooth surfaces, whereas spiky structures and bare metal had a negative effect on endothelial migration. Thrombogenicity assays under static and flow conditions showed that platelet adhesion was reduced on the flat elevations and the smooth surface, as compared to the spiky structures, the hollow design and the bare metal substrates. Surface microstructures strongly influence endothelialisation of substrates. Designing stents with surface topography which accelerates endothelialisation and reduces thrombogenicity may be of clinical benefit by improving the safety profile of coronary interventions.

Vapor-transport growth of high optical quality WSe2 monolayers

Monolayer transition metal dichalcogenides are atomically thin direct-gap semiconductors that show a variety of novel electronic and optical properties with an optically accessible valley degree of freedom. While they are ideal materials for developing optical-driven valleytronics, the restrictions of exfoliated samples have limited exploration of their potential. Here, we present a physical vapor transport growth method for triangular WSe2 sheets of up to 30 μm in edge length on insulating SiO2 substrates. Characterization using atomic force microscopy and optical microscopy reveals that they are uniform, monolayer crystals. Low temperature photoluminescence shows well resolved and electrically tunable excitonic features similar to those in exfoliated samples, with substantial valley polarization and valley coherence. The monolayers grown using this method are therefore of high enough optical quality for routine use in the investigation of optoelectronics and valleytronics.

Fabrication of Diamond Photonic Crystals with Oxide and Metallic Glasses Lattices for Terahertz Wave Control by Micro Pattering Stereolithography

Diamond lattice type photonic crystals with periodic arranged magnetic and dielectric materials can reflect the terahertz waves through Bragg diffraction. The fine diffraction lattices were fabricated successfully by using micro patterning stereolithography of computer aided designing and manufacturing methods. In this process, the photo sensitive acrylic resin paste mixed with micrometer sized metallic glass and oxide glass particles was spread on a glass substrate with 10 μm in layer thickness by using a mechanical knife edge, and cross sectional images of ultra violet ray were exposed with 2 μm in part accuracy. The high resolution exposure could be realized by using a digital micro-mirror device. The micro mirrors of 14 μm in edge length were tilted individually by piezoelectric actuators. Through the layer by layer stacking, the micrometer order metallic glass and oxide glass composite structure was formed. The magnetic and dielectric composite lattices could be obtained through the dewaxing and sintering process with the lower temperature of 400 ºC under the transition point of metallic glass and above the melting point of oxide glass. The amorphous structure formation after the heat treatment was verified by a X-ray diffraction analysis. A transmission spectrum of electromagnetic wave in terahertz frequency ranges for the formed magnetic and dielectric crystals with a diamond lattice structure was measured by using a terahertz time domain spectroscopy.

Toward Three-Dimensional Microelectronic Systems: Directed Self-Assembly of Silicon Microcubes via DNA Surface Functionalization

The huge and intelligent processing power of three-dimensional (3D) biological "processors" like the human brain with clock speeds of only 0.1 kHz is an extremely fascinating property, which is based on a massively parallel interconnect strategy. Artificial silicon microprocessors are 7 orders of magnitude faster. Nevertheless, they do not show any indication of intelligent processing power, mostly due to their very limited interconnectivity. Massively parallel interconnectivity can only be realized in three dimensions. Three-dimensional artificial processors would therefore be at the root of fabricating artificially intelligent systems. A first step in this direction would be the self-assembly of silicon based building blocks into 3D structures. We report on the self-assembly of such building blocks by molecular recognition, and on the electrical characterization of the formed assemblies. First, planar silicon substrates were functionalized with self-assembling monolayers of 3-aminopropyltrimethoxysilane for coupling of oligonucleotides (single stranded DNA) with glutaric aldehyde. The oligonucleotide immobilization was confirmed and quantified by hybridization with fluorescence-labeled complementary oligonucleotides. After the individual processing steps, the samples were analyzed by contact angle measurements, ellipsometry, atomic force microscopy, and fluorescence microscopy. Patterned DNA-functionalized layers were fabricated by microcontact printing (μCP) and photolithography. Silicon microcubes of 3 μm edge length as model objects for first 3D self-assembly experiments were fabricated out of silicon-on-insulator (SOI) wafers by a combination of reactive ion etching (RIE) and selective wet etching. The microcubes were then surface-functionalized using the same protocol as on planar substrates, and their self-assembly was demonstrated both on patterned silicon surfaces (88% correctly placed cubes), and to cube aggregates by complementary DNA functionalization and hybridization. The yield of formed aggregates was found to be about 44%, with a relative fraction of dimers of some 30%. Finally, the electrical properties of the formed dimers were characterized using probe tips inside a scanning electron microscope.

Purification of L-asparaginase II by crystallization

Here a case study of L-asparaginase II out of a recombinant Escherichia coli is presented. The target protein was obtained by simple cell disintegration and acetone precipitation. The L-asparaginase II has been crystallized in three different forms in the following microbatch crystallization. The rod-shaped crystals (∼400 μm edge length) were obtained at either 8°C or 22°C after 17 h by addition of PEG6000. The rectangular-shaped crystals were obtained after further recrystallization of the rod-shaped crystals. The rhombic-shaped crystals formed at 8°C after 12 days when cold ethanol was used instead of PEG6000. All crystallizations were performed in tris-acetate buffer (50 mmol·L−1, pH 5.1). By crystallization, the specific activity of L-asparaginase II has increased 5-fold. The protein content and the purity of the crystals were evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The more concentrated L-asparaginase II out of an extract mixture and the presence of only less minor proteins after crystallization demonstrates that crystallization is an effective and mild method to purify the target protein. The single crystal X-ray diffraction pattern reveals that the crystals are proteins and the X-ray powder diffraction (XRPD) pattern shows clearly that the crystals forming in PEG6000 and ethanol have different crystal structures.

Graphite Supported Preparation (GSP) of α-Cyano-4-Hydroxycinnamic Acid (CHCA) for Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS) for Peptides and Proteins

Graphite as MALDI matrix or in combination with other substances has been reported in recent years. Here, we demonstrate that graphite can be used as target coating supporting the crystallization of the α-cyano-4-hydroxycinnamic acid matrix. A conventional dried-droplet preparation of matrix and analyte solution on a graphite-coated metal target leads to a thin, uniform layer of cubic crystals with about 1 μm edge length. Commercially available graphite powder of 1-2 μm particle size is gently wiped over the target using a cotton Q-tip, leading to an ultra-thin, not-visible film. This surface modification considerably improves analysis of peptides and proteins for MALDI MS using conventional dried-droplet preparation. Compared with untreated targets, the signal intensities of standard peptides are up to eight times higher when using the graphite supported crystallization. The relative standard deviation in peak area of angiotensin II for sample amounts between 1 and 50 fmol is reduced to about 15 % compared with 45 % for untreated sample holders. For a quantification of 1 fmol of the peptide using an internal standard the coefficient of variation is reduced to 3.5 % from 8 %. The new graphite supported preparation (GSP) protocol is very simple and does not require any technical nor manual skills. All standard solvents for peptides and proteins can be used.