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Browsing Biomedical Engineering by Subject "microliter sample"

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    A Microstrip Transmission Line RF Biosensor: A Biosensing Device to Measure the Interaction Between Microliter Aqueous Solutions and Radio Frequencies
    (North Dakota State University, 2024) Godfrey, Mary
    Biosensors exploring the interaction between electromagnetic (EM) energy and aqueous solutions have long been an area of research interest. Previous research designs have employed various experimental setups, testing device structures, and frequency ranges to determine if property changes occur within the aqueous solutions under test after/during exposure to (EM) energy. Previous works have identified needs in the field, including smaller experimental device dimensions, a requirement of nanoliter to milliliter sampling volumes, and the ability to gather repeatable and sensitive measurements. Research Aim 1: The following dissertation questioned: Is it possible to design a sensor capable of measuring levels of interaction between RF energy and aqueous samples with reasonable reproducibility, sensitivity, and repeatability, all while being small in dimension, inexpensive to produce, and requiring microliter sample sizes? Research Aim 2: If the abovementioned sensor can be designed and verified, can it be used to measure the interaction levels between a broadband sweep of radiofrequencies and aqueous lambda DNA? In response to Research Aim 1, a millimeter-sized, microstrip transmission line biosensor with a microliter well operating on a broadband radio frequency range of 1.0-17.0 GHz was designed, simulated, and experimentally verified. Aqueous solutions, including deionized water, Tris-EDTA buffer, and lambda DNA, were loaded into the microliter well, and non-ionizing RF waves were transmitted down the transmission line. S-parameters were measured in sets to determine the interaction between the aqueous solution under test and the broadband radiofrequency sweep. Reproducibility and sensitivity were calculated for experimental data sets. Experimental data demonstrated 1) the RF biosensor’s ability to repeatably measure increasing concentrations of aqueous solutions, for example, lambda DNA diluted in Tris-EDTA buffer, and 2) a high measurement sensitivity, with the highest error value observed being 0.36%. Addressing Research Aim 2, increasing concentrations of lambda DNA diluted in Tris-EDTA buffer were experimentally measured, and reproducible trends were observed. Overall, the RF biosensor design was verified and determined to be a valid solution for measuring interaction levels between radiofrequencies and aqueous solutions of microliter quantities.