Atmospheric Pressure Mass Spectrometry of Single Viruses and Nanoparticles by Nanoelectromechanical Systems

Mass spectrometry of intact nanoparticles and viruses can serve as a potent characterization tool for material science and biophysics. Inaccessible by widespread commercial techniques, the mass of single nanoparticles and viruses (>10MDa) can be readily measured by NEMS (Nanoelectromechanical Systems) based Mass Spectrometry, where charged and isolated analyte particles are generated by Electrospray Ionization (ESI) in air and transported onto the NEMS resonator for capture and detection. However, the applicability of NEMS as a practical solution is hindered by their miniscule surface area, which results in poor limit-of-detection and low capture efficiency values. Another hindrance is the necessity to house the NEMS inside complex vacuum systems, which is required in part to focus analytes towards the miniscule detection surface of the NEMS. Here, we overcome both limitations by integrating an ion lens onto the NEMS chip. The ion lens is composed of a polymer layer, which charges up by receiving part of the ions incoming from the ESI tip and consequently starts to focus the analytes towards an open window aligned with the active area of the NEMS electrostatically. With this integrated system, we have detected the mass of gold and polystyrene nanoparticles under ambient conditions and with two orders-of-magnitude improvement in capture efficiency compared to the state-of-the-art. We then applied this technology to obtain the mass spectrum of SARS-CoV-2 and BoHV-1 virions. With the increase in analytical throughput, the simplicity of the overall setup and the operation capability under ambient conditions, the technique demonstrates that NEMS Mass Spectrometry can be deployed for mass detection of engineered nanoparticles and biological samples efficiently.Comment: 38 pages, 6 figure

3D Printing with Post-processing for Piezoelectret Energy Harvesters and Vacuum Electronics

Additive manufacturing has been at the forefront of manufacturing research with advances in basic printing techniques, materials, and post-processing schemes. This work addresses two technical challenges in the broad spectrum of 3D printed structures: (1) functional surfaces and devices; (2) the surface finishing in terms of roughness. In the first part of this dissertation, a post-fabrication process is investigated to create functional 3D printed structures that can be used for energy harvesting applications by converting mechanical energy to electricity. Chemical vapor deposition (CVD) of various Parylene layers is used to coat a thin film on top of the 3D printed polymer surfaces. The corona discharge method is then used to implant surface charges on the film to construct multi-layered energy harvesting structures. Experimentally, the prototypes can produce 12.5 µW/cm2. Then, a wearable shoe sole energy harvester has been created using 3D printing and CVD of Parylene C and tested in real-life scenarios such as walking, running, and jumping. The system can produce a peak power output of 8 µW/cm2 from a single layer design. In the second part of this dissertation, a novel surface polishing method has been developed to polish enclosed structures by 3D printed waveguide structures for vacuum electronics for high frequency applications with very stringent surface finish requirements. Magnetic particles have been used in an abrasive slurry and a linear actuator system has been developed to move a magnet. The moving magnetic field can move the slurry inside an enclosed structure to polish the surface. The system has been tested on sample waveguide structures made of copper powders via the electron beam 3D printing process with an initial surface roughness of 40 µm. By using the method developed in this dissertation, the surface roughness has been reduced to reach 1.5 µm in a waveguide

Stereolithography (SLA) 3D printing of ascorbic acid loaded hydrogels: A controlled release study

Patients’ genetic characteristics, age, gender, diet, and lifestyle affect the success of medical treatment. The treatment’s effectiveness can be increased by using personalized medication; however, using conventional large-scale drug production methods can restrict tablet geometry and drug dosage combinations. To create these personalized drugs, 3D printing has been studied as an alternative production method. In this study, stereolithography 3D printing is used to create custom tablet geometries using a novel biocompatible photochemistry consisting of ascorbic acid (AA) encapsulated in a poly(ethylene glycol) dimethacrylate (PEGDMA)-based polymer network and polymerized using riboflavin as a photoinitiator. The printing process is customized for the chemistry and different geometries (small and large tablet, coaxial annulus, 4-circle pattern and honeycomb pattern) with surface area to volume ratios ranging from 0.6 to 1.83 are fabricated. The tablets’ microstructures are examined and the cumulative release rates in gastrointestinal conditions are analyzed periodically for 6 h. After 1 h of release, honeycomb and coaxial annulus tablet gels exhibit higher release rates at approximately 80%. The experimental data is fitted to empirical release kinetic models and the Higuchi model is shown to yield the best fitting results. Overall, by using a novel biocompatible photochemistry and 3D printing we have shown that it is possible to successfully load and release ascorbic acid as a model agent, opening up a new class of manufacturing protocols to encapsulate ascorbic acid and other water-soluble vitamins as well as many different drugs for drug delivery applications

Cumhuriyet Dönemi’nde metroloji ve Ulusal Metroloji Enstitüsü

Ankara : İhsan Doğramacı Bilkent Üniversitesi İktisadi, İdari ve Sosyal Bilimler Fakültesi, Tarih Bölümü, 2014.This work is a student project of the The Department of History, Faculty of Economics, Administrative and Social Sciences, İhsan Doğramacı Bilkent University.by Öztürk, İbrahim Mert

Efficient sensing of single viruses and nanoparticles by nanomechanical sensors integrated with ion lenses

Nanoelectromechanical Systems (NEMS) resonators can be used to detect, weigh and identify single nanoparticles and viruses. Given their small footprint, however, NEMS are plagued by low analyte detection rate since the active sensing cross-sections to capture analyte particles is very small. Here we report on the development of an on-chip focusing lens operating in air and integrated with the NEMS sensor. The integrated system increases the capture efficiency by orders of magnitude, and allows for operation under ambient conditions to measure the mass of nanoparticles and virions. With this system, mass spectrum of nanoparticle samples and mammalian viruses at biologically relevant concentrations can be characterized within less than 30 minutes

Atmospheric pressure mass spectrometry of single viruses and nanoparticles by nanoelectromechanical systems

Mass spectrometry of intact nanoparticles and viruses can serve as a potent characterization tool for material science and biophysics. Inaccessible by widespread commercial techniques, the mass of single nanoparticles and viruses (>10MDa) can be readily measured by nanoelectromechanical systems (NEMS)-based mass spectrometry, where charged and isolated analyte particles are generated by electrospray ionization (ESI) in air and transported onto the NEMS resonator for capture and detection. However, the applicability of NEMS as a practical solution is hindered by their miniscule surface area, which results in poor limit-of-detection and low capture efficiency values. Another hindrance is the necessity to house the NEMS inside complex vacuum systems, which is required in part to focus analytes toward the miniscule detection surface of the NEMS. Here, we overcome both limitations by integrating an ion lens onto the NEMS chip. The ion lens is composed of a polymer layer, which charges up by receiving part of the ions incoming from the ESI tip and consequently starts to focus the analytes toward an open window aligned with the active area of the NEMS electrostatically. With this integrated system, we have detected the mass of gold and polystyrene nanoparticles under ambient conditions and with two orders-of-magnitude improvement in capture efficiency compared to the state-of-the-art. We then applied this technology to obtain the mass spectrum of SARS-CoV-2 and BoHV-1 virions. With the increase in analytical throughput, the simplicity of the overall setup, and the operation capability under ambient conditions, the technique demonstrates that NEMS mass spectrometry can be deployed for mass detection of engineered nanoparticles and biological samples efficiently