Junior Engineer, Bioreactors

Team: Science

Location: Redwood City, CA

Commitment: Full-time

Workplace Type: onsite

Salary:

 Total compensation also includes generous equity and benefits including:

• Medical, dental, and vision insurance for you and your family

• 401(k) plan with 4% matching.

• Flexible time off and 10 company holidays per year.

• Paid parental leave.

• Annual learning & development stipend.

• Monthly Longevity stipend.

• Daily Retro-sponsored lunch and snacks.

Retro develops therapies for diseases driven by the biology of aging. We focus on cellular reprogramming and autophagy to rejuvenate cell and tissue function with the ultimate aim of adding 10 years to healthy human lifespan.

We’re building a mission-driven team of accomplished and kind individuals who embrace our startup culture of rapid iteration, transparency, and versatility.

We are hiring a new member of the team who will expand Retro’s capabilities by building, maintaining, and scaling custom bioreactor systems used for automated cell culture. This is a highly hands-on “builder” role at the intersection of precision assembly, fluidics, sensors, electronics, and automation. In this role, expect to be at the bioreactor—assembling hardware, improving designs, strengthening reliability, and enabling scientists to run more experiments confidently.

About you:

You are a hands-on engineer at heart—someone who loves building complex, reliable systems. You balance rigor and documentation with a bias toward unconventional approaches and rapid iteration.

You’ve likely worked in environments like precision manufacturing, instrument assembly, or hardware-heavy R&D where you were close to the hardware—not just designing it, but building it, debugging it, and improving it. Ideally, you have a track record of transforming prototype systems into closed, production-ready platforms, within cGMP environments.

What you’ll do in this role:

• Assemble and maintain custom-built bioreactors producing cutting edge cell therapies (combination of fluidics, electronics).

• Source and modify the right parts (fittings, electronics, fluidics) for bioreactor building and expansion.

• Own pre-experiment setup readiness, including sterilization/autoclave workflows, sterile assembly, and end-to-end system preparation.

• Develop repeatable build/assembly processes (fixtures, checklists, standards) to reduce setup time and variability across runs.

• Troubleshoot and resolve hardware/software issues quickly (leaks, pressure/flow instability, sensor drift, electrical faults, controller errors).

• Support in-experiment operations by monitoring sensors, pressure, weights, and media changes, and responding rapidly to deviations.

• Implement and improve process monitoring and control strategies to maintain optimal cell culture environments.

• Partner with process development scientists to integrate bioreactor systems into workflows and scale experimental throughput.

• Train lab personnel on proper instrument use and best practices; update workflows and SOPs as systems evolve.

• Produce and maintain rigorous documentation and records (maintenance logs, calibrations, QC checks, SOPs, and design documentation) to support internal knowledge sharing, regulatory submissions, and GMP transition.

You might thrive in this role if you have:

• A degree in biomedical engineering, mechanical engineering, electrical engineering, mechatronics, or equivalent hands-on experience.

• Proven experience building and assembling hardware systems (not only designing)—especially where precision and repeatability matter (instrumentation, precision manufacturing, hardware R&D, etc.).

• Strong mechanical aptitude (comfortable reading manuals/schematics, diagnosing failures, working with fittings/tubing/fluid paths).

• Comfort working across disciplines (fluidics, sensors, electronics, mechanical assemblies) and learning new skills quickly.

• Great organizational skills and attention to detail—able to keep systems, logs, and procedures clean and reliable in a fast-moving lab environment.

• A love of complex systems and machines, the ability to troubleshoot on the fly, and the desire to continuously improve processes.

• Pride in your work - you don’t wait around for a work order when you notice a problem, you feel ownership of the labs’ well-being.

Bonus if you have:

• Worked with bioreactors and/or automation equipment.

• Worked with equipment in a GMP environment.

• Experience sourcing parts and coordinating with vendors (e.g., McMaster-Carr and similar suppliers); ability to quickly find, evaluate, and procure the right components.

• Basic programming or scripting skills for instrument control or data analysis.

• Basic electronics skills (circuits, breadboards, microcontrollers, sensors, displays).

• 3D printing and rapid prototyping experience.

• Worked in startup or “scrappy build” environments where requirements evolve quickly.

*At Retro, we don’t use titles internally. New hires join as a “Member of X Team.”