Hydrogen Tracer Gas Detector PCB Design

Hi, I am looking for an electronics/PCB engineer to design a complete working PCB for my portable hydrogen tracer gas detector used for plumbing leak detection. The purpose of the device is to detect hydrogen/forming gas (typically 5% H₂ / 95% N₂) escaping from underground or concealed water pipes. Main functions required 1. Hydrogen gas sensor interface • Designed around a suitable high-sensitivity H₂ sensor. • I want good stability, fast response and the lowest practical PPM detection range. • Sensor should preferably be replaceable/modular. 2. Active air sampling • Small vacuum/sample pump draws air from a long probe into the sensor chamber. • PCB should control/power the pump. • Provision for suitable pump driver/protection circuitry. 3. Microcontroller • Suitable MCU such as ESP32, STM32 or another recommended controller. • Engineer can recommend the best option based on reliability, simplicity and cost. 4. Display • Small LCD/OLED/TFT display. • Display should show hydrogen concentration/signal level. • Preferably show PPM if the selected sensor supports reliable PPM measurement. • Battery level/status should also be displayed. 5. Audible leak indication • Buzzer/beeper. • Beeping frequency should increase as detected gas concentration increases. 6. Visual indication • LED indicators and/or graphical sensitivity bar on the display. • Increasing gas level should be easily visible to the operator. 7. Controls • Power ON/OFF. • Zero/calibration function. • Sensitivity adjustment if required. • Simple controls suitable for field use. 8. Power system • Rechargeable lithium battery. • USB-C charging preferred. • Battery charging/protection circuit. • Voltage regulation for the MCU, sensor, display and pump. • Low-battery protection/indication. 9. PCB requirements • Compact PCB suitable for a handheld detector. • Proper grounding, filtering and power-supply design because sensor readings must be stable. • Connectors for: • Hydrogen sensor • Pump • Display if separate • Battery • Buzzer • Buttons/switches • Any external probe/sensor connection required What I need from the engineer The project must be delivered as a complete manufacturing-ready PCB design, not only a schematic. Final delivery must include: • Complete schematic • PCB layout • Gerber files • BOM – Bill of Materials • CPL / Pick-and-Place file • JLCPCB-compatible manufacturing files if possible • PCB fabrication files • Assembly drawings • Component reference/designator information • Complete editable/source design files • Firmware/source code for the microcontroller • Programming instructions • Wiring/connection diagram • Basic testing procedure • Calibration procedure for the hydrogen sensor I want to be able to upload the Gerber + BOM + CPL directly to JLCPCB for PCB manufacturing/assembly. Please do not use obsolete or extremely difficult-to-purchase components. Components should preferably be available from JLCPCB/LCSC, Mouser, DigiKey, RS, Element14 or other common suppliers. Important This is currently a working prototype / R&D project, so my priority is: Stable readings → fast gas response → reliable field operation → simple design → easy manufacturing → easy servicing. I do not need unnecessary complicated features at this stage. Before starting the PCB layout, I would like you to provide: 1. Proposed block diagram 2. Recommended hydrogen sensor 3. Recommended MCU 4. Recommended sample pump 5. Proposed power architecture 6. Estimated PCB size 7. Main components you plan to use