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Open Access Publications from the University of California

Scholarly Works (3 results)

  • Thesis
  • Peer Reviewed
UC Riverside Electronic Theses and Dissertations (2016)

We demonstrate a simple and inexpensive sensor capable of weighing microgram- scale objects in fluid. When objects flow through a glass tube that is vibrating at its resonance frequency, the frequency changes by an amount that is inversely proportional to the object’s buoyant mass. By measuring this frequency change, microgram objects can be weighed in fluid with nanogram-scale resolution. These sensors are easily fabricated, require no labels or tags, and are versatile, making them a valuable instrument for both in situ and laboratory measurements. They are fully automated and can measure any appropriately sized object in a wide range of biological, physical, and chemical applications. Using resonating glass tubes, we demonstrate the mass change detected in zebrafish (D. rerio) embryos as they are exposed to various toxicants, the water uptake and germination of dry seeds as they are put in water, and degradation rates in biomaterials in different fluid media.

Aside from the experimental data from two separate resonator geometries, we also present simulations on other geometries that can be explored for these sensors. We explore the advantages and disadvantages in each geometry and potential sources of measurement error associated with the resonators. The simulations allow us to predict the resolution and the quality factor of the resonator before a prototype is developed.

We took advantage of various rapid prototyping techniques, including 3D printing for developing these sensors. In this process, we discovered that 3D printed parts produce a toxic effect in zebrafish embryos. This observation led to a separate project, in which we assessed the toxicity of printed parts from two main classes of commercial 3D printers, fused deposition modeling and stereolithography. We used zebrafish embryos, a widely used model organism in aquatic toxicology and monitored them for rates of survival, hatching, and developmental abnormalities. We found that parts from both types of printers were measurably toxic, with STL-printed parts significantly more toxic than FDM-printed parts. We also developed a simple post-printing treatment (exposure to ultraviolet light) that largely mitigates the toxicity of the STL-printed parts. Our results call attention to the need for strategies for the safe use and disposal of 3D-printed parts and printer waste materials.

    Cover page: Resonating Mass Sensors for Detecting Microgram Scale Objects in Fluids
    • Article
    • Peer Reviewed
    UC Riverside Previously Published Works (2017)
    Measurements of an objects fundamental physical properties like mass, volume, and density can offer valuable insights into the composition and state of the object. However, many important biological samples reside in a liquid environment where it is difficult to accurately measure their physical properties. We show that by using a simple piece of glass tubing and some inexpensive off-the-shelf electronics, we can create a sensor that can measure the mass, volume, and density of microgram-sized biological samples in their native liquid environment. As a proof-of-concept, we use this sensor to measure mass changes in zebrafish embryos reacting to toxicant exposure, density changes in seeds undergoing rehydration and germination, and degradation rates of biomaterials used in medical implants. Since all objects have these physical properties, this sensor has immediate applications in a wide variety of different fields including developmental biology, toxicology, materials science, plant science, and many others.
      Cover page: Measuring the mass, volume, and density of microgram-sized objects in fluid.Creative Commons 'BY' version 4.0 license
      • Article
      • Peer Reviewed
      UC Riverside Previously Published Works (2017)
      Measurements of an object's fundamental physical properties like mass, volume, and density can offer valuable insights into the composition and state of the object. However, many important biological samples reside in a liquid environment where it is difficult to accurately measure their physical properties. We show that by using a simple piece of glass tubing and some inexpensive off-the-shelf electronics, we can create a sensor that can measure the mass, volume, and density of microgram-sized biological samples in their native liquid environment. As a proof-of-concept, we use this sensor to measure mass changes in zebrafish embryos reacting to toxicant exposure, density changes in seeds undergoing rehydration and germination, and degradation rates of biomaterials used in medical implants. Since all objects have these physical properties, this sensor has immediate applications in a wide variety of different fields including developmental biology, toxicology, materials science, plant science, and many others.
        Cover page: Measuring the mass, volume, and density of microgram-sized objects in fluid.
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