Development of the schematic of a heartbeat and oximetry sensor

I'm looking for someone to develop the schematic of a heartbeat sensor for electronic purposes. The sensor technology I would like to use is Photoplethysmography (PPG). I am only needing assistance with the hardware aspects of the sensor, not the software. Therefore, the contractor must have experience with design and manufacturing of hardware focused on precision optoelectronics. Please include with your bid how you can help meet this need, as well as any portfolio pieces that showcase your experience working on similar projects. Thank you for your interest in this project.