Now showing items 1-14 of 14

    • Aqueous Multiphase Systems of Polymers and Surfactants Provide Self-Assembling Step-Gradients in Density 

      Mace, Charles R.; Akbulut, Ozge; Kumar, Ashok Ashwin; Shapiro, Nathan D.; Derda, Ratmir; Patton, Matthew Reiser; Whitesides, George McClelland (American Chemical Society, 2012)
      This Communication demonstrates the generation of over 300 phase-separated systems—ranging from two to six phases—from mixtures of aqueous solutions of polymers and surfactants. These aqueous multiphase systems (MuPSs) ...
    • Broadly Available Imaging Devices Enable High-Quality Low-Cost Photometry 

      Christodouleas, Dionysios; Nemiroski, Alex; Kumar, Ashok Ashwin; Whitesides, George McClelland (American Chemical Society (ACS), 2015)
      This paper demonstrates that, for applications in resource-limited environments, expensive microplate spectrophotometers that are used in many central laboratories for parallel measurement of absorbance of samples can be ...
    • Combining Step Gradients and Linear Gradients in Density 

      Kumar, Ashok Ashwin; Walz, Jenna A.; Gonidec, Mathieu; Mace, Charles R.; Whitesides, George McClelland (American Chemical Society (ACS), 2015)
      Combining aqueous multiphase systems (AMPS) and magnetic levitation (MagLev) provides a method to produce hybrid gradients in apparent density. AMPS—solutions of different polymers, salts, or surfactants that spontaneously ...
    • Density-Based Separations in Aqueous Multiphase Systems: Tools for Biological Research and Low-Cost Diagnostics 

      Kumar, Ashok Ashwin (2014-06-06)
      Cells often exist in heterogeneous mixtures. Density provides a property to separate several types of cells from the mixed sample in which they originate. Density-based separation methods provide a standard method to ...
    • Diagnosis of iron deficiency anemia using density-based fractionation of red blood cells 

      Hennek, Jonathan; Kumar, Ashok Ashwin; Wiltschko, Alexander Bame; Patton, Matthew Reiser; Lee, Si Yi Ryan; Brugnara, Carlo; Adams, Ryan Prescott; Whitesides, George McClelland (Royal Society of Chemistry (RSC), 2016)
      Iron deficiency anemia (IDA) is a nutritional disorder that impacts over one billion people worldwide, it causes permanent cognitive impairment in children, fatigue in adults, and suboptimal outcomes in pregnancy. IDA can ...
    • Enrichment of Reticulocytes from Whole Blood using Aqueous Multiphase Systems of Polymers 

      Kumar, Ashok Ashwin; Lim, Caeul; Moreno, Yovany; Mace, Charles R.; Syed, Abeer; Van Tyne, Daria Natalie; Wirth, Dyann F.; Duraisingh, Manoj T.; Whitesides, George McClelland (Wiley-Blackwell, 2014)
      This paper demonstrates the enrichment of reticulocytes by centrifuging whole blood through aqueous multiphase systems (AMPSs)—immiscible phases of solutions of polymers that form step-gradients in density. The interfaces ...
    • Evaluation of a Density-Based Rapid Diagnostic Test for Sickle Cell Disease in a Clinical Setting in Zambia 

      Kumar, Ashok A.; Chunda-Liyoka, Catherine; Hennek, Jonathan W.; Mantina, Hamakwa; Lee, S. Y. Ryan; Patton, Matthew R.; Sambo, Pauline; Sinyangwe, Silvester; Kankasa, Chipepo; Chintu, Chifumbe; Brugnara, Carlo; Stossel, Thomas P.; Whitesides, George M. (Public Library of Science, 2014)
      Although simple and low-cost interventions for sickle cell disease (SCD) exist in many developing countries, child mortality associated with SCD remains high, in part, because of the lack of access to diagnostic tests for ...
    • Fractionating Polymer Microspheres as Highly Accurate Density Standards 

      Bloxham, William Henry; Hennek, Jonathan; Kumar, Ashok Ashwin; Whitesides, George McClelland (American Chemical Society (ACS), 2015)
      This paper describes a method of isolating small, highly accurate density-standard beads and characterizing their densities using accurate and experimentally traceable techniques. Density standards have a variety of ...
    • From the Bench to the Field in Low-Cost Diagnostics: Two Case Studies 

      Kumar, Ashok Ashwin; Hennek, Jonathan; Smith, Barbara L; Kumar, Shailendra; Beattie, Patrick; Jain, Sidhartha; Rolland, Jason P.; Stossel, Thomas Peter; Chunda-Liyoka, Catherine; Whitesides, George McClelland (Wiley-Blackwell, 2015)
      Despite the growth of research in universities on point-of-care (POC) diagnostics for global health, most devices never leave the laboratory. The processes that move diagnostic technology from the laboratory to the field—the ...
    • High-Sensitivity Measurement of Density by Magnetic Levitation 

      Nemiroski, Alex; Kumar, Ashok Ashwin; Soh, Siowling; Harburg, Daniel V.; Yu, Hai-Dong; Whitesides, George McClelland (American Chemical Society (ACS), 2016)
      This paper presents methods that use Magnetic Levitation (MagLev) to measure very small differences in density of solid diamagnetic objects suspended in a paramagnetic medium. Previous work in this field has shown that, ...
    • A Paper-Based “Pop-up” Electrochemical Device for Analysis of Beta-Hydroxybutyrate 

      Wang, Chien-Chung; Hennek, Jonathan; Ainla, Alar; Kumar, Ashok Ashwin; Lan, Wen-Jie; Im, Judy S; Smith, Barbara S.; Zhao, Mengxia; Whitesides, George McClelland (American Chemical Society (ACS), 2016)
      This paper describes the design and fabrication of a “pop-up” electrochemical paper-based analytical device (pop-up-EPAD) to measure beta-hydroxybutyrate (BHB)—a key biomarker for diabetic ketoacidosis—using a commercial ...
    • Separation of Nanoparticles in Aqueous Multiphase Systems through Centrifugation 

      Akbulut, Ozge; Mace, Charles R.; Martinez, Ramses Valentin; Kumar, Ashok Ashwin; Nie, Zhihong; Patton, Matthew Reiser; Whitesides, George M. (American Chemical Society (ACS), 2012)
      This paper demonstrates the use of aqueous multiphase systems (MuPSs) as media for rate-zonal centrifugation to separate nanoparticles of different shapes and sizes. The properties of MuPSs do not change with time or during ...
    • Universal mobile electrochemical detector designed for use in resource-limited applications 

      Nemiroski, Alex; Christodouleas, Dionysios; Hennek, J. W.; Kumar, Ashok Ashwin; Maxwell, E. J.; Fernandez-Abedul, M. T.; Whitesides, George McClelland (Proceedings of the National Academy of Sciences, 2014)
      This paper describes an inexpensive, handheld device that couples the most common forms of electrochemical analysis directly to “the cloud” using any mobile phone, for use in resource-limited settings. The device is designed ...
    • Using Magnetic Levitation to Separate Mixtures of Crystal Polymorphs 

      Atkinson, Manza B. J.; Bwambok, David K.; Chen, Jie; Chopade, Prashant D.; Thuo, Martin M.; Mace, Charles R.; Mirica, Katherine A.; Kumar, Ashok Ashwin; Myerson, Allan S.; Whitesides, George McClelland (Wiley-VCH Verlag Berlin, 2013)
      Magnetische Levitation (MagLev) ist eine einfache Trennmethode für Kristallpolymorphe mit Dichteunterschieden (Δρ) von nur 0.001 g cm−3. Für vier organische Verbindungen wurden dichtebasierte Trennungen verschiedener ...