Digital Microfluidics Control System II P15610

Previous state - The previous control system is not self contained and uses a class AB amplifier which makes the system large and nonmodular. Desired state - A fully enclosed control system that efficiently operates the DMF chip while providing accurate feedback. Project Goals - Make key improvements to functionality of control system, and complete all assigned deliverables. ● Repeatable, consistent droplet motion. ● Durable, lightweight, modular design. Constraints - Use provided DMF chip, control fluid droplets using electrowetting, use DI water as test fluid, ensure compatibility with peripheral hardware and GUI. Phase One: Problem Definition Problem Statement

Phase One: Problem Definition Engineering Requirements

Phase One: Problem Definition DropBot

Phase One: Problem Definition Functional Decomposition

Phase Two: Subsystem Identification System Layout

Phase One: Problem Definition Morphological Chart

Phase Two: Subsystem Identification Original CAD Models

Phase Two: Subsystem Identification Original External Design Components: 3 Enclosures and Lid 1 Fan and Fan Guard Electrical Ports: USB, BNC, 40 pin connector, Power Vent Grommets

Phase Three: Design and Testing Output Board: PCB layout

Phase Three: Design and Testing Output Board: PCB layout

● Takes amplified signal from amplifier chooses which pin on DMF chip to apply high voltage ● Consists of: o HV Solid State Relays o Shift Registers (Load pin positions to apply voltage to) o Control Mechanism (ATMEGA) Phase Three: Design and Testing Output Board: Functionality

Phase Three: Design and Testing Output Board: Functionality ATMEGA Shift Register Off Board 40 HV Relays DMF Chip

Phase Three: Design and Testing Input Board: Functionality

Phase Three: Design and Testing Input Board: Functionality 1pF: steady state voltage of 29mV 200pF: steady state voltage of 5.00V Rise time: <10ms

Phase Three: Design and Testing Input Board: Functionality 60pF: steady state voltage of 1.693V 61pF: steady state voltage of 1.720V Granularity: 27mV/pF or: 5.5 q- level/pF

-Total simulated current draw: <25mA -Noise: input filter to buffer limits frequency generator noise -Large capacitive loading: Zener diode limits output (below) -Output noise: two-stage low-pass filter Phase Three: Design and Testing Input Board: Functionality

-Absolute values of measured capacitances ranged from 30pF to 170pF -Capacitance changes over time in the minutes -Capacitance differences sub-1pF Phase Three: Design and Testing Input Board: Previous Data Graphs from Dr. Michael Schertzer “Automated detection of particle concentration and chemical reactions in EWOD devices”

Phase Three: Design and Testing Input Board: PCB Layout

-Input Board was tested using the designed circuit and outputted the following waveform before full- wave rectification -This demonstrates that the signal is voltage-varying and can demonstrate changes in magnitude -Phase detection remains untested, however the preliminary circuit was promising Phase Three: Design and Testing Input Board: Experimental Output

Phase Three: Design and Testing Signal Generator: PCB Layout

Phase Three: Design and Testing Signal Generator: PCB Layout

- (+)9 V p-p from signal generator amplified to 120 V p-p between ~ kHz Phase Three: Design and Testing Amplifier Functionality

- Simulated with a 600uH Resonant Converter Transformer Phase Three: Design and Testing Amplifier Functionality

- Breadboarded setup of amplifier design Phase Three: Design and Testing Amplifier: Preliminary Design

-Output waveforms at 10kHz and 100kHz respectively Phase Three: Design and Testing Amplifier: Preliminary Results

Phase Three: Design and Testing Amplifier: PCB Layout

Phase Three: Design and Testing Fault Detector: PCB Layout

Phase Three: Design and Testing Indicator: PCB Layout

-Cosel +/- 15 V 1.7A -Cosel +5 V 2A Phase Three: Design and Testing Power Supplies

Phase Three: Integration

Machining of Enclosures

Phase Four: Final Design

Performance vs. Requirements

Housing ● 10 pin ribbon cable connector ● Protective paint coating Input Board ● Purchase DropBot input board or modify existing software to work with current board Amplifier ● Modify design to use BNC connector instead of SMA Power Supply ● Switch to using power supply from P15611 Opportunities for Future Work