LOC IC HV Generation and On-Chip Electronic Systems Integration

  • Author / Creator
    Sloan, David
  • The BIOMEMS interdisciplinary research group has been working to produce single chip Lab-on-Chip systems for genetic diagnostic applications. By bringing a genetic diagnostic platform down to the size of a single Lab-on-Chip integrated circuit we can enable fast testing at the point of care. One significant impediment to single-chip operation is the requirement of high-voltage supplies for driving capillary electrophoresis experiments and actuating electrostatic systems. My research focuses on on-chip high voltage generation and control systems, improvements on analog circuits involved in heater control, and optical detection, as well as digital logic and synthesis. The high voltage systems are described as they relate to Lab-on-Chip genetic diagnostic platforms requiring high voltage signaling to drive capillary electrophoresis experiments, and enable future Lab-on-Chip systems to use electrostatic valving. In this work I present a fully integrated 300 V charge pump capable of producing a 3mW, 300 V signal from a 5 V USB port. In order to accommodate future Lab-on-Chip devices with high valve counts, the high voltage switches used in previous generations of Lab-on-Chip integrated circuits have been redesigned using novel control signal level-shifting circuits. The new high voltage switching devices occupy one half the silicon area of previous designs, and consume less power from the high voltage supply when switching. High voltage sensing was also considered, in order to produce programmable high-voltage regulation. I propose and demonstrate novel high voltage sensing device is proposed and has been fabricated which occupies only 1.2% of the layout area of previous generations of high voltage sensing circuits and contains no DC current path from the high voltage sense line to ground. The heating and sensing circuits, use for PCR amplification, built into previous generations of Lab-on-Chip integrated circuits had limited current driving capabilities and were sensitive to contact resistance between the microfluidic and CMOS chips. In my work I have increased the current driving capabilities, increased the control logic power resolution, and added 4-point sensing to reduce the impact of heater contact resistance on heater temperature readings. These changes increase the current drive capabilities from 300mA to 1A, and driver resolution from 8-bits to 10-bits, to allow for a larger range of microfluidic heater designs. The improvements made in heater element resistance sensing, in addition to providing 4-point direct element sensing, allow for the use of dedicated thermistor sensing elements, should direct element sensing prove insufficient. Circuit redesigns are discussed for the on-chip optical sensing devices in order to simplify chip illumination requirements for optical tests. The circuits proposed demonstrated the feasibility of alternate designs, but will need further work to obtain similar noise floors to earlier work. Finally, improvements have been made to the digital logic and digital synthesis process used in our Lab-on-Chip integrated circuit designs.

  • Subjects / Keywords
  • Graduation date
    Fall 2018
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
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