Tim W.

Experience

• Engineering Consultant Electronics Design · Self-employed Jan 2012 – Present 14 yrs 7 mos United States Completed 100+ projects for various applications.
  
  • Designed embedded systems providing the following functions.
  o Wireless interfaces. WIFI, BT, and non-standard FSK interfaces ESP32.
  o LCD touchscreen displays.
  o Various types of applications interfacing with many different types of actuators and sensors. Stepper Motors, Servo Motors, Linear Actuators.
  o The controllers were primarily ATMEL and Microchip devices.
  o ESP32.
  o Raspberry PI.
  o Wrote firmware and PC based user interfaces for the controllers. The embedded code was written in C under The Arduino IDE, MPLAB, and Atmel Studio. The UI software was written in Visual Basic and C Sharp under Visual Studio.
  • Designed several motion control systems including.
  o Choosing motors and actuators (servo motors, stepper motors, linear motors, solenoids, voice coil actuators, and others) given speed, force, torque, inertial load, and power requirements.
  o Choosing or designing the embedded controller for the system and writing the firmware.
  o Designing or choosing amplifiers and feedback components.
  o Writing PC based user interface. The code was written in C Sharp, Visual Basic, or the tools provided by the motion controller manufacturer.
  o Designing mechanical components for the systems.
  • Designed several switched mode power supplies and battery management solutions.
  • Designed several rechargeable battery and solar powered systems.
  • Created PCB layouts for most of the projects listed above. The majority were done with Eagle. Some were also done with Altium Designer, OrCAD, and KiCad.
  • Created PCB layouts from client’s schematic designs or prototypes.
• Electrical Engineer (Contract Position) Axsun Technology · Full-time Jan 2010 – Aug 2012 2 yrs 7 mos Billerica, MA, United States Axsun Technologies designs and manufactures products employing Optical Coherence Tomography (OCT) techniques. They serve the Medical and industrial markets. I worked as an Electrical Design Engineer for Medical Products. These products are used to examine retinas and to capture cardiac arterial images from a catheter inside the artery. The advantage of OCT over other imaging techniques is that it can be used to image tissue to a depth unlike Ultrasonic or MRI techniques. Micron resolution at a depth of 2mm can be achieved.
  
  • Designed a Handpiece PCB based on the ADI Blackfin Microprocessor for a Fiber- optic Cardiac Catheter System. The Handpiece is used by surgeon to control the catheter within the patient. It spins and drives the catheter while illuminating the artery and collecting image data. The PCB has the following sub-systems.
  
  o A 3A Stepper Driver used to drive a lead screw which moves the catheter through the artery while imaging.
  o A Brushless hall commutated motor driver used to spin the catheter at 80,000 RPM while collecting imaging data.
  o SDRAM and Flash Memory, used for program storage and execution, and FRAM used for settings unique to the Handpiece the board is driving.
  o An RFID Reader/Writer used read and write to an RFID Chip embedded in the catheter. The chip is read when the catheter is installed in the Handpiece and written to thereafter. The purpose is so it may not be reused. Information about the Catheter is also stored in the chip such as the diameter of the catheter.
  o Serial and USB interfaces providing communication with the computer running the system.
  o A keypad interface used by the surgeon to control the handpiece. Turn imaging on or off, move the Pull Back motor, eject the Catheter...
  o Switching Regulators to provide DC voltages for the various sub-systems.
  o Onboard diagnostics to monitor various voltages in the system and to perform a Power on Self-Test.
  • Designed and debugged a Functional Test fixture for both the PCB and the Handpiece.
  • Tested all the PCBs produced and wrote a procedure to do so.
  • Initialized and tested all the Handpieces and trained others to do so. Wrote the initialization test procedure.
  • Documented the PCB and wrote ECOs to release it and all its associated cables.
  • Performed system EMC compliance tests (FCC and CE). Debugged failures and made modifications to achieve compliance.
• Electrical Engineering Consultant Seahorse BioScience · Full-time May 2008 – May 2010 2 yrs Billerica, MA, United States Seahorse BioScience designs and manufactures extra cellular flux analyzers used for in-vitro cellular assays. Using LEDs, fiber-optics and fluorescent probes, oxygen consumption rates and acidification rates are measured in live cells. This process is done twice. The first measurement is a baseline of these rates. The second measurement is done after exposing the cells to various reagents to measure their effect on cellular energetics.
  
  • Implemented processes to improve PCB yields from 50% to 95+%. PCBs represent approximately 30% of the product material cost.
  • Designed fixtures, wrote software, and wrote procedures to automate PCB testing. Reduced test time from several hours to approximately 20 minutes.
  • Redesigned a transimpedance amplifier with a gain of 10 billion to improve reliability.
  • Designed PIC based temperature controller PCB to control temperatures in the instrument within 0.1°C.
  • Acted as liaison between consultants and manufacturing for the introduction of a fluidics system. Duties included.
  o Documenting the instrument.
  o Procuring the parts for and supervising technicians on the beta build.
  o Training manufacturing and service personnel on assembly, test, installation, and repair.
  o Obtaining regulatory approvals for the instrument.
  • Obtained regulatory approval for instruments (TUV & CE). Debugged EMC, EMI, and safety problems.
• Principal Electrical Engineer Aushon BioSystems · Part-time Mar 2005 – Nov 2007 2 yrs 8 mos Billerica, MA, United States Aushon BioSystems was a biotech startup, which designed and manufactured a protein deposition robot used to create biological assays. I was the fourth employee in the company. Aushon has since been acquired by Quanterix. Their system contains a large XYZ stage, which uses servo driven lead screws with linear encoder feedback to transfer samples from microtiter plates to substrates. The system has a positional resolution of ½ micron.
  Developed the system electronics architecture.
  Designed all electrical systems (7 PCBs, 80+ cables), and specified all purchased components for both alpha and production systems).
  Developed the system throughput model to optimize performance and guarantee stability.
  Wrote motion control code to test the systems.
  Purchased all electrical components for the first build of 5 systems.
  Debugged and tested initial systems for shipment.
  Modified and tested the system to qualify for CE compliance.
  Supervised technicians on engineering and production builds.
  Wrote assembly and test procedures.
  Installed and serviced several of the initial systems.
• Principal Electrical Engineer Affymetrix · Full-time May 2000 – May 2005 5 yrs Billerica, MA, United States Affymetrix manufactures biochips used in genetic assays. The Bedford Division, where I worked, designed and manufactured the instruments used by customers to prepare and perform experiments with the chips.
  
  Designed a PCB for a laser scanning confocal microscope which provided a bridge between a PC104 Controller and s other system components. (Laser, chip transport, actuators, etc.).
  Performed initial field upgrades to the scanner of enhancements developed by Engineering.
  Designed 6805 based controller for a biochip autoloader used to feed and remove biochips in and out of the scanner and maintain them at a constant temperature.
  Designed electronics for a PC104 based controller, used to control a four axis well plate transfer robot.
  Wrote software to control the above-mentioned robot in C.
• Project Manager Genetic Microsystems · Full-time May 1997 – May 2000 3 yrs Woburn, MA, United States Lead a team of Software, Hardware, and Mechanical Engineers in the development and release to production of a Genetic Microarraying System.
  * Worked with beta customers to develop enhancements for production systems.
  * Designed System Electronics Architecture.
  * Worked with manufacturing to facilitate release to production
  
  Principal Electrical Engineer
  
  * Designed a Pixel Clock PCB for a Laser Scanning Confocal Microscope.
  * Designed a Laser Power Monitor for a fluorescence scanner.
  * Designed and specified all of the electronics for a DNA microarrayer.*
• Principal Electrical Engineer General Scanning · Full-time Feb 1986 – Feb 1997 11 yrs Watertown, MA, United States Developed electronics architecture and designed electronics on the following projects:
  Holographic CT image printer.
  Microfiche film printer.
  Several CT scan image printers.
  Laser Scanning Print Engine Interface. This was in ISA board, which buffered a 60 MB image in DRAM and transferred the data over a proprietary interface to be printed on X-ray film by a laser-scanning engine.
  Galvanometer Servo Amplifiers.
  Nuclear Medicine Film Printer Remote Control.