TY - CONF A1 - Hernández García, María Amparo T1 - SAF-based optical biosensor with 3D-printed free-form optics for targeted explosives immuno-detection N2 - Guaranteeing safety and security of citizens requires a significant effort and innovative tools from national and international agencies and governments, especially when it comes to the field of explosives detection. The need to detect Improvised Explosive Devices (IEDs) and Home-made Explosives (HMEs) at a point of suspicion, has grown rapidly due to the ease with which the precursors can be obtained and the reagents synthesised. The limited availability of immunoanalytical tools for HME detection presents an opportunity for the development of new devices, which enable a rapid detection and recognise the target analyte with high specificity and sensitivity. In this work, we introduce an optical biosensor for highly specific and sensitive HME detection. The immunoassay system is placed in a hydrogel environment permeable to the analyte and transparent to light interrogating the fluorescently labelled antibodies. The readout of the immunoanalytical system is realized with Supercritical Angle Fluorescence (SAF), an advanced microscopy technique. To accomplish this, we made use of recent, commercial high resolution (< 22 µm) Liquid Crystal Display 3D printers to fabricate a parabolic optical element with high refractive index (RI>1.5) and transmission values (>90%) from photo-resin. Aiming at a new generation of sensors, which not only can meet the requirements of trace detection, but can also be used for substance identification, the combination of immunoanalytical recognition with SAF detection offers a modularity and versatility that is principally well suitable for the measurements of target analytes at trace levels. T2 - 8th International conference in Biosensing Technology CY - Seville, Spain DA - 12.05.2024 KW - 3D printing KW - Biosensor KW - Fluorescence KW - Explosives PY - 2024 AN - OPUS4-60561 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hernandez Garcia, Maria Amparo T1 - Optical biosensor using free form prototyped elements for targeted explosives immunodetection N2 - Ensuring the safety and security of citizens necessitates a considerable investment of resources and the development of innovative tools by national and international agencies and governments, particularly in the context of explosives detection [1]. The necessity for the detection of improvised explosive devices (IEDs) and homemade explosives (HMEs) at the point of suspicion has increased exponentially due to the simplicity with which the precursors can be obtained, and the reagents synthesised. The restricted availability of immunoanalytical instruments for the detection of homemade explosives (HMEs) offers a valuable opportunity for the development of innovative devices that can rapidly identify and recognise the target analyte with high specificity and sensitivity [2]. In this study, we present the development of an optical biosensor for highly specific and sensitive HME detection. The immunoassay system is situated within a matrix that is permeable to the target analyte and transparent to light, which enables the interrogation via fluorescence. The immunoanalytical system's readout is achieved through the utilisation of supercritical angle fluorescence (SAF), an advanced microscopy technique. To this end, we employed recent, commercially available high-resolution (less than 22 μm) liquid crystal display SLA printers to fabricate a free-form parabolic optical element with a high refractive index (RI greater than 1.5) and transmission values exceeding 90% from commercial photo-resins. The objective is to develop a new generation of sensors that can not only meet the requirements of trace detection but also be used for substance identification. The combination of immunoanalytical recognition with SAF detection offers a modular and versatile solution that is particularly well suited to the measurement of target analytes at trace levels. T2 - ANAKON 2025 CY - Leipzig, Germany DA - 10.03.2025 KW - Biosensor KW - SAF KW - Free-form optics KW - 3D printing KW - Security PY - 2025 AN - OPUS4-62802 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hernandez Garcia, Maria Amparo T1 - Characterization and testing of commercial photo-resins for the fabrication of free-form optical elements with standard LCD 3D printer for advanced opto-biosensing applications N2 - Optical biosensors often show remarkable performance and can be configured in many ways for sensitive, selective, and rapid measurements. However, the high-quality and advanced optical assemblies required to read out the sensor signals, for example, Total Internal Reflection Fluorescence (TIRF) or Supercritical Angle Fluorescence (SAF) microscopy, which necessitate complex and expensive optical elements. Particularly in optical method development, researchers or developers are often confronted with limitations because conventional manufacturing processes for optical elements can be restrictive in terms of design, material, time, and cost. Modern and high-resolution 3D printing techniques make it possible to overcome these challenges and enable the fabrication of individualized and personalized free-form optical components, which can reduce costs and significantly shorten the prototyping timeline—from months to hours. In this work, we use a modern, high-resolution (< 22 µm) commercial Liquid Crystal Display (LCD)-based 3D printer, for which we spectroscopically and physically characterized commercial photo-resins printable with the LCD technique in the first step (Figure 1). The aim was not only to produce a printed element with a high surface quality that mitigates the inner filter effects caused by attenuation (high optical density (OD) due to reflection and scattering), but also to select a material with a high refractive index (RI>1.5) and high transmission values (>90% transmittance) in the visible to near-infrared spectral range (approx. 450 – 900 nm) that exhibits little or no autofluorescence. Using a selection of suitable resins, lenses and free-form optical elements were manufactured for comparison with standard glass or plastic counterparts. T2 - Europt(r)ode XVI CY - Birmingham, England DA - 24.03.2024 KW - 3D-printing KW - Optics KW - Photopolymerization KW - Sensors KW - Rapid prototyping PY - 2024 AN - OPUS4-59875 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hernandez Garcia, Maria Amparo T1 - Low-cost production of free-form optical components via standard LCD 3D printing for advanced opto-sensing N2 - Nowadays, the use of complex optical elements is increasing also in applications such as miniaturized (bio)chemical opto-sensors. However, this can easily result in considerably high costs, time-consuming fabrication processes and the restricted availability of unconventional optics, which is especially problematic during the development phase of such devices. In this work, we propose LCD 3D printing as an alternative cost-effective technique, which is not only user-friendly but also free of design constrains enabling to fabricate free-form optics. A physical and spectroscopic characterization of six commercially available resins was performed together with the replication of optics and chemical sensing applications as a proof of concept. The optical transparency of the commercial mixtures was evaluated to discriminate the materials optically not suitable for the fabrication of transparent optical elements. Among the six resins, five were considered optimally transparent, with an optical transmittance >85% in the visible spectra range. However, fluorescence analysis of two of these commercial resins, assessed with an excitation-emission matrix (EEM), showed a high autofluorescence in the most common spectral working area of 410–600 nm. Therefore, only three commercial resins were considered for an in-depth evaluation. Ensuring that the refractive index (RI) of the resins complies with that of the most common optical materials, i.e., possesses a RI ~1.5 like polymers such as plexiglass or polycarbonate and glasses such as N-BK7, another important feature is an adequate surface quality of the printed objects. This could be accomplished with a dedicated post-treatment procedure allowing to reach a surface roughness of Rq = 0.07 μm, which agrees well with the values of common glass (Rq = 0.05 μm) and polymer lenses (Rq = 0.075 μm). To demonstrate the suitability of the 3D printed lenses, two different chemical sensors earlier published by us were replicated using the equivalent 3D printed lenses, i.e., a strip test for hydrocarbon detection using a 3D printed aspheric condenser and a microfluidic device for the determination of water chlorination using two cylindrical 3D printed lenses.[1, 2] Independent of the optical material used for the lenses, both assays exhibit similar calibration curves and results (see Figure 1 for one example), suggesting that LCD 3D printing is a suitable technique for the fabrication of free-form optics that allows to design, fabricate and test unconventional optics for miniaturized sensors in a much faster and distinctly less expensive manner. T2 - How to develop a sensor? Academic Approaches vs. Industrial Interests (EU Training School) CY - Kaiserslautern, Germany DA - 18.09.2024 KW - 3D-printing KW - Optics KW - Photopolymerization KW - Rapid prototyping KW - Sensors PY - 2024 AN - OPUS4-61444 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hernandez Garcia, Maria Amparo T1 - Fabrication of low-cost free-form optical elements with standard LCD 3D printer for advanced opto-sensing and imaging applications N2 - Nowadays, more and more complex optical elements are used in optical applications, but this can lead to high costs, a time-consuming manufacturing process and limited availability of unconventional elements. Therefore, in this work, we propose LCD 3D printing as alternative cost-effective technique, which is not only user-friendly but also free from design constrains and enables the fabrication of free-form optics. The tested polymeric materials showed promising results for printed optics and optical applications. In addition, 3D printed optical elements were evaluated in terms of their suitability in selected applications with opto-chemical sensors and imaging techniques, with results comparable to those obtained with the corresponding glass optical elements. T2 - 12th European Optical Society Annual Meeting CY - Naples, Italy DA - 09.09.2024 KW - 3D-printing KW - Optics KW - Photopolymerization KW - Rapid prototyping KW - Sensors PY - 2024 AN - OPUS4-61442 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -