Mixed-Signal PCB Design & Analog Front-End Design

Transmissive Pulse Oximeter

• Managed a 4-person engineering team, managing timelines and design reviews to ensure on-time hardware and firmware integration

• Led schematic capture and board layout of a mixed-signal PCB in Altium Designer, integrating battery charging and an I2C display for real-time SpO2, heart rate, and temperature readings

• Designed a custom analog front-end, implementing a precision transimpedance amplifier, 3rd-order Sallen-Key filter, and 380x gain stage to process nano-amp photodiode signals

• Engineered a precision bandgap reference and PTAT circuit for LED thermal drift compensation, achieving 0.5°C accuracy and validating a constant voltage within 1mV over a 20°C to 50°C sweep

• Developed embedded C/C++ firmware, utilizing DSP and an adaptive peak detection algorithm to achieve SpO2 accuracy within 2% and heart rate tracking within 3 bpm

Analog Circuit Design Mixed-Signal PCB Design & Layout Altium Designer Embedded C/C++ DSP
I2BL Project Poster

Wireless Bioelectronic System Design & Hardware Validation

Interconnected and Integrated Bioelectronics Lab Research Project

Electrolyte imbalances are critical factors in major organ failure, contributing to an average of 13 deaths daily in the United States. Thus, developing an accurate, real-time in-body biochemical sensing system is vital for effective disease management and early organ failure detection. Current methodologies' limitations are: 1) blood draws are time-consuming, one-time measurements; 2) wearable biosensors have detection delays with limited sensing capabilities; and 3) current implantables are bulky, battery-powered, with limited selectivity. We are developing a battery-free, implantable biochemical sensing system designed for localized organ monitoring. The system includes a flexible wearable paired with a passive implantable that uses inductive coupling for wireless power transfer and data transmission. We were previously challenged with low sensitivity, poor sensor performance, and vulnerability to distance-induced distortions on the signal. Here, we introduce an optimized dual-pair system that accurately measures the sensor response by removing baseline variations caused by distance distortions. Our approach leverages a reference implantable to reject environmental variations, thereby enabling isolation of the sensor response. The implantable was redesigned to minimize sensor noise, achieving a 4x improvement in signal-to-noise ratio. Mathematically informed impedance matching enhanced the system's sensitivity by 340%, and the wearable was further miniaturized by 32%. Mathematical modeling paired with a distance rejection algorithm provided accurate vertical distance prediction and enabled the back-calculation of the analyte concentration from the sensor. This work validates a low-noise, high-sensitivity wireless sensing system that resolves a critical barrier by removing environmental variations from sensor readings, enabling accurate in-body concentration determination.

RF PCB Design, Layout & Assembly Impedance Matching Hardware Debugging Data Acquisition EAGLE
LLNL Project Poster

Power Harvesting Test System Design & Characterization

Lawrence Livermore National Laboratory Research Project

• Engineered a custom hardware testing system for triboelectric nanogenerators, scaling the maximum measurable voltage by 4000%

• Led analog circuit design and board assembly of high-voltage buffers and transimpedance amplifiers for micro-amp signals processing

• Conducted electrical characterization and modeling of display actuators in liquid crystal and electrophoretic display technologies

• Automated 100+ mechanical actuation experiments using robotic test equipment, analyzing datasets in Python and Excel to optimize power transfer efficiency and system performance

Analog Circuit Design Test System Development Electrical Characterization
RF Transmitter Project

RF Transmitter & Receiver Design

27 MHz Wireless RF Communication System

• Engineered and assembled a 27 MHz wireless RF communication system as part of the UCLA IEEE WRAP project, managing the hardware lifecycle from initial design to final board integration

• Designed and optimized BJT-based RF circuits, including oscillators, amplifiers, buffers, filters, and mixers, to ensure efficient and reliable signal transmission and reception

• Executed schematic capture and board layout for custom RF transmitter and receiver PCBs in KiCad, validating theoretical circuit performance through LTspice and MATLAB system simulations

• Conducted physical hardware integration and bench testing utilizing oscilloscopes and spectrum analyzers to fine-tune signal integrity and optimize overall system performance

RF Circuit Design PCB Design & Layout LTspice KiCAD
Audio Project

Custom Mixed-SignalPCB Design & Embedded Audio Processing

Audio Amplifier with 7-Band Visualizer

• Designed and assembled a custom mixed-signal PCB featuring a stereo audio amplifier integrated with a real-time 7-band frequency visualizer

• Engineered the analog audio system utilizing operational amplifiers and stereo buffers to implement user-controlled volume, gain, and bass boost functionality for enhanced audio performance

• Programmed embedded C++ firmware on a microcontroller interfaced with a hardware frequency analyzer to process analog audio signals and render the spectrum on an OLED display

Mixed-Signal PCB Design C++ I2C Communication Audio Engineering

Embedded Security System & Sensor Integration

Arduino-Based Security System

• Designed and prototyped an Arduino-based access control system, integrating RFID, ultrasonic sensors, and a membrane keypad for real-time intrusion detection

• Developed embedded C++ firmware to drive an OLED display, creating a menu interface for users to configure security settings and manage access credentials

• Interfaced multiple analog and digital peripherals, linking sensor inputs directly to RGB LEDs and buzzers for immediate visual and auditory alarm feedback

Embedded C++ Microcontroller Programming Sensor Integration