Portable Multimodal Analyzer PCB Design

We are developing a portable, handheld research instrument that combines two measurement modalities in a single pen-form device: 1. ELECTRICAL IMPEDANCE SPECTROSCOPY (EIS) 4-wire (tetrapolar) configuration. Frequency sweep 100mHz to 200kHz. Phase angle resolution ≤ 0.1°. Impedance range 10Ω to 10MΩ. Precision analog front-end IC (SPI interface). Shielded cable connector for external probe (Lemo or circular DIN, IP44). 2. OPTICAL SPECTROSCOPY Hamamatsu C12880MA MEMS spectrometer (SPI). Multi-wavelength LED driver: 4 channels (405 / 530 / 625 / 850 nm), sequential, PWM-controlled, current-regulated ±1%. SMA905 fiber optic connector. This project centres on a single-board solution that brings electrical impedance spectroscopy and optical spectroscopy together for chemical and wet-lab work. The heart of the design is a precision 4-wire analog front-end that must resolve phase-angle bioimpedance from 100 mHz up to 200 kHz with very low drift and noise. That accuracy takes priority over every other subsystem, so component choice, guard routing, Kelvin connections and calibration hooks all need special care. Beyond the impedance path, the board has to host a Hamamatsu C12880MA MEMS spectrometer over SPI, plus a four-channel LED driver delivering 405 nm, 530 nm, 625 nm and 850 nm illumination. The digital side funnels data out via MQTT and ultimately into an SQL back-end, so the MCU and network stack should be laid out for clean signal isolation and straightforward firmware bring-up. Power is supplied by a Li-Po pack with on-board fuel gauging, USB-C charging and 5 V/3 V rails sized for simultaneous analog, digital and LED loads. DELIVERABLES Schematic PDF · PCB layout source files · Gerber + drill files · BOM (MPN ) · Assembly drawing Acceptance is based on the analog front-end meeting its phase-angle accuracy targets, clean optical routing for the spectrometer, and a power section that maintains noise performance under worst-case load.

Project ID: 40483978