Resume

• 2009

  Massachusetts Institute of Technology

• 2006

  Massachusetts Institute of Technology

  University of California

  Riverside

  Massachusetts Institute of Technology

• 1999

  William

  Grover

  University of California

  Berkeley

  University of California

  Riverside

  University of California

  Berkeley

  Associate Professor

  University of California

  Riverside

  Doctor of Philosophy - PhD

  Chemistry

  University of California

  Berkeley

• 1995

  Bachelor of Science - BS

  Chemistry

  University of Tennessee

  Knoxville

• 1994

  University of Tennessee

  Knoxville

  University of Tennessee

  Knoxville

• 1991

  High School Diploma

  Science Hill High School

• Adobe Illustrator

  Python (Programming Language)

  Microfluidics

  Higher Education

  Analytical Chemistry

  AutoCAD

  Sensors

  LaTeX

  Chemistry

  Next Generation Science Standards

  Python

  Medical Diagnostics

  Research

  LabVIEW

  Monolithic membrane valves and diaphragm pumps for practical large-scale integration into glass microfluidic devices

  Richard A. Mathies

  Eric T. Lagally

  Chung N. Liu

  Monolithic elastomer membrane valves and diaphragm pumps suitable for large-scale integration into glass microfluidic analysis devices are fabricated and characterized. Valves and pumps are fabricated by sandwiching an elastomer membrane between etched glass fluidic channel and manifold wafers. A three-layer valve and pump design features simple non-thermal device bonding and a hybrid glass-PDMS fluidic channel; a four-layer structure includes a glass fluidic system with minimal fluid-elastomer contact for improved chemical and biochemical compatibility. The pneumatically actuated valves have less than 10 nl dead volumes

  can be fabricated in dense arrays

  and can be addressed in parallel via an integrated manifold. The membrane valves provide flow rates up to 380 nL/s at 30 kPa driving pressure and seal reliably against fluid pressures as high as 75 kPa. The diaphragm pumps are self-priming

  pump from a few nanoliters to a few microliters per cycle at overall rates from 1 to over 100 nl/s

  and can reliably pump against 42 kPa pressure heads. These valves and pumps provide a facile and reliable integrated technology for fluid manipulation in complex glass microfluidic and electrophoretic analysis devices.

  Monolithic membrane valves and diaphragm pumps for practical large-scale integration into glass microfluidic devices

  Richard A. Mathies

  An integrated microfluidic processor is developed that performs molecular computations using single nucleotide polymorphisms (SNPs) as binary bits. A complete population of fluorescein-labeled DNA “answers” is synthesized containing three distinct polymorphic bases; the identity of each base (A or T) is used to encode the value of a binary bit (TRUE or FALSE). Computation and readout occur by hybridization to complementary capture DNA oligonucleotides bound to magnetic beads in the microfluidic device. Beads are loaded into sixteen capture chambers in the processor and suspended in place by an external magnetic field. Integrated microfluidic valves and pumps circulate the input DNA population through the bead suspensions. In this example

  a program consisting of a series of capture/rinse/release steps is executed and the DNA molecules remaining at the end of the computation provide the solution to a three-variable

  four-clause Boolean satisfiability problem. The improved capture kinetics

  transfer efficiency

  and single-base specificity enabled by microfluidics make our processor well-suited for performing larger-scale DNA computations.

  An integrated microfluidic processor for single nucleotide polymorphism-based DNA computing

  Gerald F. Joyce

  Richard A. Mathies

  Brian M. Paegel

  In vitro evolution of RNA molecules requires a method for executing many consecutive serial dilutions. To solve this problem

  a microfluidic circuit has been fabricated in a three-layer glass-PDMS-glass device. The 400-nL serial dilution circuit contains five integrated membrane valves: three two-way valves arranged in a loop to drive cyclic mixing of the diluent and carryover

  and two bus valves to control fluidic access to the circuit through input and output channels. By varying the valve placement in the circuit

  carryover fractions from 0.04 to 0.2 were obtained. Each dilution process

  which is composed of a diluent flush cycle followed by a mixing cycle

  is carried out with no pipetting

  and a sample volume of 400 nL is sufficient for conducting an arbitrary number of serial dilutions. Mixing is precisely controlled by changing the cyclic pumping rate

  with a minimum mixing time of 22 s. This microfluidic circuit is generally applicable for integrating automated serial dilution and sample preparation in almost any microfluidic architecture.

  Microfluidic serial dilution circuit

  Richard A. Mathies

  Jeffrey L. Bada

  Frank J. Grunthaner

  Pascale Ehrenfreund

  Robin H.C. Ivester

  Andrew D. Aubrey

  James R. Scherer

  The Mars Organic Analyzer (MOA)

  a microfabricated capillary electrophoresis (CE) instrument for sensitive amino acid biomarker analysis

  has been developed and evaluated. The microdevice consists of a four-wafer sandwich combining glass CE separation channels

  microfabricated pneumatic membrane valves and pumps

  and a nanoliter fluidic network. The portable MOA instrument integrates high voltage CE power supplies

  pneumatic controls

  and fluorescence detection optics necessary for field operation. The amino acid concentration sensitivities range from micromolar to 0.1 nM

  corresponding to part-per-trillion sensitivity. The MOA was first used in the lab to analyze soil extracts from the Atacama Desert

  Chile

  detecting amino acids ranging from 10-600 parts per billion. Field tests of the MOA in the Panoche Valley

  CA

  successfully detected amino acids at 70 parts per trillion to 100 parts per billion in jarosite

  a sulfate-rich mineral associated with liquid water that was recently detected on Mars. These results demonstrate the feasibility of using the MOA to perform sensitive in situ amino acid biomarker analysis on soil samples representative of a Mars-like environment.

  Development and evaluation of a microdevice for amino acid biomarker detection and analysis on Mars

  Richard A. Mathies

  Erik C. Jensen

  It is shown that microfabricated polydimethylsiloxane membrane valve structures can be configured to function as transistors in pneumatic digital logic circuits. Using the analogy with metal-oxide-semiconductor field-effect transistor circuits

  networks of pneumatically actuated microvalves are designed to produce pneumatic digital logic gates (AND

  OR

  NOT

  NAND

  and XOR). These logic gates are combined to form 4- and 8-bit ripple-carry adders as a demonstration of their universal pneumatic computing capabilities. Signal propagation through these pneumatic circuits is characterized

  and an amplifier circuit is demonstrated for improved signal transduction. Propagation of pneumatic carry information through the 8-bit adder is complete within 1.1 s

  demonstrating the feasibility of integrated temporal control of pneumatic actuation systems. Integrated pneumatic logical systems reduce the number of off-chip controllers required for lab-on-a-chip and microelectromechanical system devices

  allowing greater complexity and portability. This technology also enables the development of digital pneumatic computing and logic systems that are immune to electromagnetic interference.

  Micropneumatic digital logic structures for integrated microdevice computation and control

  Richard A. Mathies

  Erik C. Jensen

  Robin H.C. Ivester

  Novel latching microfluidic valve structures are developed

  characterized

  and controlled independently using an on-chip pneumatic demultiplexer. These structures are based on pneumatic monolithic membrane valves and depend upon their normally-closed nature. Latching valves consisting of both three- and four-valve circuits are demonstrated. Vacuum or pressure pulses as short as 120 ms are adequate to hold these latching valves open or closed for several minutes. In addition

  an on-chip demultiplexer is demonstrated that requires only n pneumatic inputs to control 2^(n-1) independent latching valves. These structures can reduce the size

  power consumption

  and cost of microfluidic analysis devices by decreasing the number of off-chip controllers. Since these valve assemblies can form the standard logic gates familiar in electronic circuit design

  they should be useful in developing complex pneumatic circuits.

  Development and multiplexed control of latching pneumatic valves using microfluidic logical structures