Imprint Stamp Research Articles

Near-field probing of surface plasmon polariton formation in imprinted gold nanoisland arrays

Large-area imprinting stamps with nanometer-scale features are a rapidly developing area of research in plasmonics. In integrated photonic structures, surface plasmon (SPs) and surface plasmon polaritons (SPPs) are tuned by selecting both the appropriate wavelength and the angle of incidence of the excitation light. The resulting exponential fields can be studied by an optical technique such as scanning near-field optical microscopy (SNOM). Here, we report on the application of the aperture-type SNOM technique to characterize, at nanoscopic and microscopic scales, the formation of the SPPs and the beat pattern formed with the superposition of SPs and the effective component of the probing light formed in discrete metallic nanostructures of Au fabricated on imprinting stamps. We discuss a model to describe the beat pattern in terms of this superposition and demonstrate that the dominant SPs have a transverse nature. Our experiments are supported by modeling the optical response and near-field in gold nanostructures using the simulation tool Tidy3D. Our results provide a straightforward way to investigate and characterize SPPs at the nanostructure level.

Investigation of Inkjet-Printed Masks for Fast and Easy Photolithographic NIL Masters Manufacturing.

Modern optical systems often require small, optically effective structures that have to be manufactured both precisely and cost-effectively. One option to do this is using nanoimprint lithography (NIL), in which the optical structures are replicated as masters using a stamping process. It would also be advantageous to manufacture the master structures quickly and easily. A master manufacturing process based on a photolithographic image of an inkjet-printed mask is presented and investigated in this paper. An essential element is that a deliberate blurring of the printed structure edge of the mask is used in the photolithographic process. Combined with the use of a non-linear photoresist, this allows for improved edge geometries of the master structure. We discuss the inkjet-printed photomask, the custom photolithography system to prevent imaging of the printing dot roughness and the manufacturing processes of NIL polymer masks as well as their subsequent stamp imprinting. Finally, it was shown that stamp geometries with a width of 1.7 µm could be realised using inkjet-printed photomasks in the master manufacturing process. This methodology opens up the potential of fast and simple master manufacturing for the development and manufacturing of optical elements.

Improved Performance of All-Inorganic Perovskite Light-emitting Diodes via Nanostructured Stamp Imprinting.

Halide perovskites are emerging emitters with excellent optoelectronic properties. Contrary to the large grain fabrication goal in perovskite solar cells, perovskite light-emitting diodes (PeLEDs) based on small grain enable efficient radiative recombination because of relatively higher charge carrier densities due to spatial confinement. However, achieving small-sized grain growth with superior crystal quality and film morphology remains a challenge. In this work, we demonstrated a nanostructured stamp thermal imprinting strategy to boost the surface coverage and improve the crystalline quality of CsPbBr3 film, particularly confine the grain size, leading to the improvement of luminance and efficiency of PeLEDs. We improved the thermal imprinting process utilizing the nanostructured stamp to selectively manipulate the nucleation and growth in the nanoscale region and acquire small-sized grain accompanied by improved crystal quality and surface morphology of the film. By optimizing the imprinting pressure and the period of the nanostructures, appropriate grain size, high surface coverage, small surface roughness and improved crystallization could be achieved synchronously. Finally, the maximum luminance and efficiency of PeLEDs achieved by nanostructured stamp imprinting with a period of 320 nm are 67600 cd/m2 and 16.36 cd/A, respectively. This corresponds to improvements of 123 % in luminance and 100 % in efficiency, compared to that of PeLEDs without the imprinting.

Tuning the feature size of nanoimprinting stamps: A method to enhance the flexibility of nanoimprint lithography

In the field of nanoimprinting lithography, fabricating large-area imprinting stamps is often the most time- and resource-consuming step. Specifically in research, it is often not reasonable to produce a new imprinting stamp for each new experimental configuration. Therefore, the lack of flexibility in feature sizes makes prototyping and tailoring the feature sizes according to their application challenging. To overcome these restrictions, we developed an imprinting stamp reproduction and tuning method which enables the size of the features of existing imprinting stamps to be tuned within nanometer precision. For replication, we first fabricate a chromium nanoisland array on silicon dioxide using the to-be tuned imprinting stamp. Then, the silicon dioxide is anisotropically etched in a reactive ion etching process with chromium as a hard mask. The formed replica of the imprinting stamp is subsequently tuned in an isotropic etching step with hydrofluoric acid. The method enables us to tune the size of the features of our nanoimprinting stamps within nanometer precision without influencing their shape with a yield above 96%. The tuned stamps are then used to fabricate metal nanoisland arrays with the respective tuned sizes. To evaluate the influence of the feature sizes, we exemplarily study the plasmonic resonance of gold nanoisland arrays fabricated using stamps with different feature diameters. Here, we see a good agreement between measured and simulated plasmonic resonance wavelengths of the samples. Hence, with the tuning method, we can tailor specific size-dependent properties of our nanoisland arrays according to individual experiments and applications.

A Self‐Assembly Method for Tunable and Scalable Nano‐Stamps: A Versatile Approach for Imprinting Nanostructures

AbstractIn nanoimprint lithography (NIL), the imprinting stamp's fabrication is still a significant cost factor among the consumables. Bottom‐up lithography approaches based on a phase‐separation of polymer blends can provide a cost‐effective route for fabricating these stamps. Today's polymers used to prepare phase‐separated nanostructures (PSN), however, exhibit low glass transition temperatures. As a result, the PSN are prone to in‐plane stamp distortions in the presence of high imprinting pressure and temperature, limiting their practical relevance for NIL. Here, the realization of mechanically and thermally stable PSN‐based imprinting stamps for NIL systems via a phase‐separation of a homopolymer/inorganic–organic hybrid polymer blend is reported. It is demonstrated that these imprinting stamps are easily tunable and scalable by adjusting the formulation of homopolymer/hybrid polymer mixture and deposition conditions. Feature sizes in PSN ranging from a few μm down to 100 nm are achieved through an interplay of these factors. As demonstrations of the envisioned applications, the developed imprinting stamps are integrated into a roll‐to‐roll NIL system for patterning a polystyrene thin‐film. Moreover, light management is demonstrated by nanopatterning of a perovskite semiconductor in plate‐to‐plate process. The nanopatterned perovskite film achieves an integrated absorption and a photoluminescence emission peak increase of 7%rel and 121%rel, respectively.

Multiscale surface modified magneto-mechano-triboelectric nanogenerator enabled by eco-friendly NaCl imprinting stamp for self-powered IoT applications.

In this paper, we demonstrated a multiscale micro- and nano-structured magneto-mechano-triboelectric nanogenerator (MMTENG) enabled by a salt particle imprinting process to power an internet of thing (IoT) sensor. The fine salt particles were utilized to form a multiscale structure on a triboelectric polymer film by mechanical pressure via an eco-friendly, low-cost, and simple process, thereby reinforcing the contact triboelectrification and electrostatic induction. The surface modified MMTENG can generate an open-circuit peak-to-peak voltage of 851 V, a short-circuit current of 155 μA, and a maximum peak power of 10.3 mW under an AC magnetic field of 8 Oe. The energy device also presented output stability over 124 million operating cycles. Finally, the electricity of the surface enhanced MMTENG device was directly utilized to power an IoT temperature sensor with integration of an energy harvester, energy conversion circuit, and storage capacitor.

Label-Free Detection of Staphylococcus aureus Based on Bacteria-Imprinted Polymer and Turn-on Fluorescence Probes.

The effective identification and quantitative determination of Staphylococcus aureus is a major public health concern. Here, an innovative strategy that combines a bacteria-imprinted polydimethylsiloxane film for bacterial recognition and fluorescence resonance energy transfer platform for turn-on fluorescence sensing is demonstrated. The bacteria-imprinted polydimethylsiloxane film was facilely fabricated to generate corresponding specific sites on the polydimethylsiloxane surface via stamp imprinting using Staphylococcus aureus as template followed by modification with 1H,1H,2H,2H-perfluorooctyltriethoxysilane. The fluorescence resonance energy transfer platform was developed through electrostatic interaction between citrate-functional copper clusters and dopamine-stabilized gold nanoparticles. When the Staphylococcus aureus are present, the 1H,1H,2H,2H-perfluorooctyltriethoxysilane-modified bacteria-imprinted polydimethylsiloxane film can precisely capture the target; subsequently, the negatively charged bacteria compete with citrate-functional copper clusters and bind to dopamine-stabilized gold nanoparticles, leading to the fluorescence recovery of citrate-functional copper clusters. The entire detection process was achieved within 135 min, showing a wide linear calibration response from 10 to 1 × 107 cfu mL-1 with a low detection limit of 11.12 cfu mL-1. Furthermore, the recoveries from spiked samples were from 97.7 to 101.90% with relative standard derivations lower than 10%. The established label-free assay of measuring Staphylococcus aureus is rapid, sensitive, specific, and efficient.

3D Micro/Nanopatterning of a Vinylferrocene Copolymer.

In nanoimprint lithography (NIL), a pattern is created by mechanical deformation of an imprint resist via embossing with a stamp, where the adhesion behavior during the filling of the imprint stamp and its subsequent detachment may impose some practical challenges. Here we explored thermal and reverse NIL patterning of polyvinylferrocene and vinylferrocene-methyl methacrylate copolymers to prepare complex non-spherical objects and patterns. While neat polyvinylferrocene was found to be unsuitable for NIL, freshly-prepared vinylferrocene-methyl methacrylate copolymers, for which identity and purity were established, have been structured into 3D-micro/nano-patterns using NIL. The cross-, square-, and circle-shaped columnar structures form a 3 × 3 mm arrangement with periodicity of 3 µm, 1 µm, 542 nm, and 506 nm. According to our findings, vinylferrocene-methyl methacrylate copolymers can be imprinted without further additives in NIL processes, which opens the way for redox-responsive 3D-nano/micro-objects and patterns via NIL to be explored in the future.

Biomimetic Moth-eye Anti-reflective Poly-(methyl methacrylate) Nanostructural Coating

This study reports a simple imprinting method for the fabrication of biomimetic moth-eye antireflective polymethyl methacrylate (PMMA) nanostructures on the surface of the substrate. The antireflection structured silicon was obtained by Reactive Ion Etching (RIE) method. By using the antireflection structured silicon substrate as the imprinting stamp, the biomimetic moth-eye polymer structures showed tapered holes, whose depth and periodicity were around 780 nm and 580 nm, respectively. The reflectance of the resulting PMMA structures was reduced from 10% to less than 1% in the wavelength range from 300 nm to 1600 nm. This simple methodology can be scaled up via self-loading and nanoimprinting, which may have a promising application in optoelectronic devices and solar cells.

Creating anodic alumina nanochannel arrays with custom‐made geometry

AbstractPorous anodic alumina oxide (AAO) is one of the most commonly used nanotemplates for growing arrays of nanoparticles, nanowires, nanocomposites, and nanoarchitectures because its pores, which are of a very uniform size, can grow longitudinally into arrays of self‐aligned nanochannels with an extremely high aspect ratio. Furthermore, under specific combinations of anodization voltage and electrolyte, the lateral positions of nanochannels can self‐organize into arrays of two‐dimensional hexagonally close‐packed lattices with domain sizes on the order of few tens of lattice units. The domain size can be greatly increased by prepatterning the Al surface with custom‐designed nanoconcaves prior to the anodization process. The concaves guide the growth fronts of nanochannels and lead to the formation of an ideally long‐range ordered lattice of nanochannel array. Such concaves have been fabricated by many methods, such as stamp imprinting, grating imprinting, and focused ion beam direct writing. In this review, we summarize the development of various methods to create AAO nanochannel arrays with custom‐made geometry and discuss the mechanism responsible for the guiding process.

Surface Molecular Imprinting Strategies: An Innovative Tool to Detect Engineered Nanoparticles in Aqueous Solutions

Within the last two to three decades, molecular imprinting has established itself a valuable technique for generating biomimetic recognition materials for a wide range of molecular and supramolecular analytes [1]. Among different target species, those with dimensions at the nanoscale are of special interest, because usually no easy-to-operate rapid tests or sensors exist for that size range. However, whereas there are some MIP for biogenic “nanoparticles”, i.e proteins [2] or viruses [3], this is not the case for engineered nanoparticles (ENPs), but for one exception: The group of D. Mandler [4] reported on a MIP based on electropolymerization to bind Au NPs. Despite successful imprinting, electropolymerized systems offer somewhat limited choice for finding optimal functional groups to interact with the respective particles. Polyadditions and radical polymerizations allow for much higher variability: We succeeded in surface imprinting of both polyurethanes and self-initiating polyacrylates, respectively, using nanoparticles as templates, as can be seen in the AFM image shown in Figure 1: It clearly reveals cavities of the desired size in the surface of a polyurethane MIP. Coating such polymers as recognition layers on quartz crystal microbalances (QCM) yields concentration-dependent frequency signals for Au NPs. One can clearly see that the MIP takes up almost ten times more NPs, than the corresponding non-imprinted polymer (NIP). Overall, such sensors hence allow for detecting Au NPs down to concentrations of a few ppm in aqueous solution with a dynamic range spanning at least 1-2 orders of magnitude in concentration. The layers efficiently exclude larger particles, as expected during imprinting. Preliminary tests reveal that ENP QCM sensors show selective behavior depending on particle diameter, particle composition and stabilizer. Furthermore, the concrete imprinting strategy has substantial influence on the sensor results: Using the same Polyurethane recipe, we developed three different imprinting protocols for ENPs, namely one-step imprinting, stamp imprinting, and sedimentation imprinting. One-step imprinting comprises mixing all monomers and templates in one batch and coating the respective sensor surface with the resulting pre-polymer. Stamp imprinting utilizes stamps containing (covalently bound) NPs to generate surface structures. Sedimentation imprinting means overlaying a spin-coated pre-polymer with the template NPs before hardening. One-step imprints did not yield any difference in sensor signal between MIP and non-imprinted polymers (NIP). Of the other two, sedimentation imprinting leads to highest overall signals (on both MIP and NIP). However, stamp imprinting leads to the largest imprinting factors: on average, MIP give rise to signals that are almost ten times larger, than those of corresponding NIP. PU-based ENP MIP have hence led to appreciable sensor responses. However, there is room to improve batch-to-batch reproducibility, because highly cross-linked polymers resulting from polyaddition turned out inhomogeneous and bearing rough surfaces. First results with self-initiating acrylates to overcome this are promising: Such MIP are indeed useful for incorporating ENPs in a reversible and quantitative manner, though imprinting effects at the current stage are lower, than in case of polyurethanes: MIP signals are usually 2-3 times higher, than NIP signals. In this light, several questions still need answers: To name only the most important ones, the exact recognition mechanisms are yet unknown; what is the exact influence of the NP core and the stabilizer shell, respectively, on the sensor signal? This notwithstanding, MIP have turned out a highly promising tool for selectively binding artificial nanoparticles from aqueous samples, which makes them interesting for e.g. food and cosmetics analysis. ACKNOWLEDGEMENTS This work was funded partly by the EU Commission in the 7th Framework Program for Research, (grant no. 280550 “INSTANT”) and partly by the Austrian Science Fund FWF, (project No. I 3568-N28), which we gratefully acknowledge. FIGURE CAPTION: AFM image and QCM sensor response, respectively, of Au-NP surface MIP. REFERENCES Ye, K. Haupt, Molecularly imprinted polymers as antibody and receptor mimics for assays, sensors and drug discovery. Anal. Bioanal. Chem. 378 (2004) 1887-1897. Naklua, R. Suedee, P. A. Lieberzeit, Dopaminergic receptor–ligand binding assays based on molecularly imprinted polymers on quartz crystal microbalance sensors. Biosens. Bioelectron. 81 (2016) 117-124. Wangchareansak, A. Thitithanyanont, D. Chuekheaw, M. P. Gleeson, P. A. Lieberzeit, C. Sangma, Influenza A virus molecularly imprinted polymers and their application in virus sub-type classification. J. Mater. Chem. B 1 (2013) 2190-2197. Kraus-Ophir, J. Witt, G. Wittstock, D. Mandler, Nanoparticle-imprinted polymers for size-selective recognition of nanoparticles. Angew. Chem. Intl. Ed. 53 (2014) 294-298. Figure 1

Nanoscale spatial limitations of large-area substrate conformal imprint lithography

We demonstrate a soft-imprint nanofabrication technique offering nanometer resolution over an area as large as a 150 mm diameter wafer. It makes use of a composite imprint stamp composed of a quaternary siloxane-modified poly-di-methyl-siloxane patterned rubber layer with a relatively high Young’s modulus that is laminated on a thin glass support. The in-plane stiffness of the stamp avoids pattern deformation over large areas, while out-of-plane flexibility allows conformal contact to be made over the entire substrate area. The stamp is used in conjunction with a novel tetra-methyl-ortho-siloxane/methyl-tri-methoxy-siloxane sol-gel imprint resist material developed to replicate nanoscale features in rigid silica at room temperature. We demonstrate better than 10 nm resolution in imprinted line gratings and individual pillars with aspect ratio as high as 5:1. Gaps as small as 6 nm can be reproduced. The patterns can be used as an etch mask to pattern 150 mm diameter silicon and quartz substrates while maintaining sub-10 nm resolution.

Recovery Behavior of Microstructured Thiol-Ene Shape-Memory Film

In this work, surface microstructurization was coupled with shape-memory polymer to generate reversibly tunable surface properties. A photopolymerizable thiol-ene composition comprising a mixture of pentaerythritol tetrakis(3-mercaptopropionate) (PETMP), 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TTT) and 2,2-dimethoxy-2-phenylacetophenone (DMPA) was used to prepare microstructured thiol-ene shape-memory film via casting and UV polymerization on the electron beam lithography fabricated arrays of 1 µm and 2 µm square pits. The mechanical deformation via compression and recovery of the surface microstructure were investigated. Results show that, after heat treatment of the deformed thiol-ene film, the recovery yields for microstructures were not worse than 90% ± 2% and 93% ± 2% for structures imprinted with 1 µm and 2 µm square pit micro imprint stamps. Additionally, heat treatment of deformed thiol-ene film resulted in the recovery of intense diffraction colors and laser diffraction patterns. This study opens up an avenue of incorporating microstructured shape-memory films for new products, e.g., optical security devices, superhydrophobic coatings, medical diagnostics and biosensors.

Resist-Free Direct Stamp Imprinting of GaAs via Metal-Assisted Chemical Etching.

We introduce a method for the direct imprinting of GaAs substrates using wet-chemical stamping. The predefined patterns on the stamps etch the GaAs substrates via metal-assisted chemical etching. This is a resist-free method in which the stamp and the GaAs substrate are directly pressed together. Imprinting and etching occur concurrently until the stamp is released from the substrate. The stamp imprinting results in a three-dimensional anisotropic etching profile and does not impair the semiconductor crystallinity in the wet-chemical bath. Hole, trench, and complex patterns can be imprinted on the GaAs substrate after stamping with pillar, fin, and letter shapes. In addition, we demonstrate the formation of sub-100 nm trench patterns on GaAs through a single-step stamping process. Consecutive imprinting using a single stamp is possible, demonstrating the recyclability of the stamp, which can be used more than 10 times. The greatest benefit of this technique is the simple method of patterning by integrating the lithographic and etching processes, making this a high-throughput and low-cost technique.

High-Resolution, High-Aspect-Ratio Printed and Plated Metal Conductors Utilizing Roll-to-Roll Microscale UV Imprinting with Prototype Imprinting Stamps

Micron-scale, high-aspect-ratio features were imprinted by a roll-to-roll process into a UV-curable polymer and used to create high-current-carrying conductive networks on plastic substrates. A stamp fabrication method was developed to create low-cost, rapidly produced roll-to-roll imprinting stamps, which can mold features from 3 μm to 1 mm wide. Isolated raised features 50 μm high were molded from a 25-μm-thick layer of UV-curable resin by displacing resin into raised features in the stamp. Substrates with imprinted capillary channels were used to form electrical conductors by printing a silver ink into reservoirs connected to the channels and allowing capillary flow to coat the channel. Copper electroless plating then filled the channels. The conductors demonstrate high resolution, high aspect ratio (∼5:1 height:width), low resistance per length, and easy integration into networks. This roll-to-roll imprinting process provides a foundation for high-throughput manufacturing of high-resolution printed el...

Multifunctional guest–host particles engineered by reversal nanoimprint lithography

Particulate polymeric microfibers with incorporated europium(III)oxide (Eu2O3) nanoparticles were introduced as a magneto-photoluminescent multifunctional material fabricated via reversal nanoimprint lithography. To specifically address the volume properties of these guest–host particles, the guest, Eu2O3, was milled down to an average particle size of 350 nm in diameter and mixed with the host-polymer, AMONIL®, before in situ hardening in the imprint stamp. The variation of the fabrication process parameters, i.e. delay time, spin coating speed, as well as the concentration of Eu2O3 nanoparticles was proven to have a significant impact on both the structure quality and the stamp release of the microfibers with respect to the formation of a thinner residual layer. Structural characterization performed by SEM revealed optimum fabrication process parameters for a homogeneous spatial distribution of Eu2O3 nanoparticles within the microfibers while simultaneously avoiding the formation of undesired agglomerates. The magneto-photoluminescent properties of Eu2O3 nanoparticles, i.e. a red emission at 613 nm and a paramagnetic response, were found to be superimposed to the optic and the diamagnetic behaviors of AMONIL®. The results imply that guest–host interdependence of these properties can be excluded and that the suggested technique enables for specific tailoring of particulate multifunctional materials with focus on their volume properties.

Single-Step Imprinting of Femtoliter Microwell Arrays Allows Digital Bioassays with Attomolar Limit of Detection.

Bead-based microwell array technology is growing as an ultrasensitive analysis tool as exemplified by the successful commercial applications from Illumina and Quanterix for nucleic acid analysis and ultrasensitive protein measurements, respectively. High-efficiency seeding of magnetic beads is key for these applications and is enhanced by hydrophilic-in-hydrophobic microwell arrays, which are unfortunately often expensive or labor-intensive to manufacture. Here, we demonstrate a new single-step manufacturing approach for imprinting cheap and disposable hydrophilic-in-hydrophobic microwell arrays suitable for digital bioassays. Imprinting of arrays with hydrophilic-in-hydrophobic microwells is made possible using an innovative surface energy replication approach by means of a hydrophobic thiol-ene polymer formulation. In this polymer, hydrophobic-moiety-containing monomers self-assemble at the hydrophobic surface of the imprinting stamp, which results in a hydrophobic replica surface after polymerization. After removing the stamp, microwells with hydrophobic walls and a hydrophilic bottom are obtained. We demonstrate that the hydrophilic-in-hydrophobic imprinted microwell arrays enable successful and efficient self-assembly of individual water droplets and seeding of magnetic beads with loading efficiencies up to 96%. We also demonstrate the suitability of the microwell arrays for the isolation and digital counting of single molecules achieving a limit of detection of 17.4 aM when performing a streptavidin-biotin binding assay as model system. Since this approach is up-scalable through reaction injection molding, we expect it will contribute substantially to the translation of ultrasensitive digital microwell array technology toward diagnostic applications.

Fast fabrication of TiO2 hard stamps for nanoimprint lithography

The fabrication of imprinting stamps plays a vital role in the nanoimprinting lithography. In this work, we proposed a facile method to fabricate TiO2 hard stamp by patterning sol-gel films. A polydimethysiloxane (PDMS) soft stamp with highly ordered micropit array was used as an original stamp to imprint the TiO2 sol which was spin coated on a quartz wafer. The nano-hardness and Young’s modulus of TiO2 hard stamp are in the range of 7.7–10.0GPa and 118.9–130.0GPa, which is much higher than the conventional PDMS material. Afterwards the TiO2 hard stamps are demonstrated in both UV and hot embossing lithography with a promising life cycle. The proposed stamp can be extended to other metal oxides, which possesses a promising prospective for large scale patterning because of the low cost and excellent mechanical durability.

Flat and highly flexible composite stamps for nanoimprint, their preparation and their limits

To reduce the overall costs, replica stamps have become more and more relevant in the past years. These replicas often are composite stamps with at least two layers, a structured top layer and a backplane. In most cases, the composite stamps are rigid, which limits their use for rolling processes or low-pressure imprints. Flexible composite stamps avoid these limitations. However, due to the flexibility, preparation-induced bending may occur. A concept to avoid such a bending will be introduced and verified by the preparation of a flat and flexible composite stamp consisting of a structured OrmoStamp top layer and a polydimethylsiloxan (PDMS) backplane. To increase the adhesion between both layers, two measures will be adopted: one relies on an increase in the surface energy of the PDMS and the other one on an increase in the interface area. Finally, these flat and highly flexible composite stamps are tested in a critical imprint situation, where particles are dusted to the substrate before imprint. Imprint defects and stamp damage due to these particles will be examined.

Molecular Imprinting Studies for Developing QCM-sensors for Bacillus Cereus

Herein we report the design of a novel molecularly imprinted polymer (MIP) for B. cereus. In a first step, we screened different polymers for their respective affinities towards B. cereus with polymer coated quartz crystal microbalance (QCM), namely polystyrene (PS), polyacrylate (PA), polyvinylpyrrolidone (PVP), polyacrylamide (PAA) and polyurethane (PU). Of these, PU and PAA revealed the highest inherent affinity to B. cereus. Light microscopy studies on polymer-coated glass plates demonstrated that PU is more promising than PAA, because the PU film contain more than three times as many bacteria compared to PAA. These experiments also showed that stamp imprinting is preferable to sedimentation imprinting. MIP was successfully transferred to QCM: Cavities generated are suitable to re-incorporate the bacteria. Both this and washing can be monitored in real-time. The sensor response time in distilled water is less than 10 min.