Senior Process Engineer, Oncology

Join a team of brilliant, passionate innovators determined to transform healthcare. At BillionToOne, we've built a category-defining, publicly traded company on Nasdaq where transparency fuels trust, collaboration drives breakthroughs, and every contribution moves the needle on our mission to make life-changing diagnostics accessible to all. We don't just aim for incremental improvements; we build products that are 10x better than anything that exists today.

Our scientists, engineers, sales executives, and visionaries are united by an unwavering commitment to changing the standard of care in prenatal and cancer diagnostics. This is where cutting-edge science meets human compassion, and every innovation you contribute helps remove the fear of the unknown from some of life's most critical medical moments.

If you're driven by purpose, energized by innovation, and ready to help shape the future of precision medicine at scale, this is where you belong.

We are looking for a Senior Process Engineer to join our growing superstar Process Engineering team in support of clinical patient testing in our high throughput CLIA lab. The Senior Process Engineer is responsible for (1) Leading the exploration of new technologies which can enable rapid scaling of our commercial assays, (2) Developing and validating new chemistry and/or process changes to enhance product performance, (3) Building out FDA/GMP/ISO compliant Scale-up, V&V, and tech transfer procedures, and (4) Serving as a mentor for junior engineers on the team. This role will enable an individual to flex their skills in process engineering, high-throughput laboratory scaleup, process improvement, statistical analysis, experimental design, and data science (amongst many more).  This role will help to build upon the strong technology and execution found within BTO’s walls. The Senior Process Engineer is an onsite position at our Menlo Park location.

• →Source and evaluate external technologies which might benefit COGS, process throughput, assay performance, turnaround time, or other key operational metrics.
• →Develop the strategies to support 2-3X annual growth in commercial volume.
• →Build upon the existing statistical Process Control system to enable ever decreasing failure rates and ever increasing assay performance.
• →Mentor junior engineers and help to establish strong skills and industry best practices across the growing PE team. 
• →Facilitate technology transfer between R&D and the clinical laboratory, identifying CPPs, process tolerances, and failure modes while ensuring that new workflows are proplery implemented in the production environment. 
• →Work with Bioinformatics and Data Science to translate assay CQAs into impactful and actionable process monitoring tools.
• →Develop new data and information handling tools to aid in efficient sample processing and process monitoring within the clinical laboratory. 
• →Apply six sigma, Design-for-quality, and 5S frameworks to existing or new processes to improve both capability, scalability, and quality of molecular diagnostic assays. 
• →Lead thorough root cause analyses to identify and solve process issues, with a mindset for long-term solutions. 

• Bachelor’s, Master’s or Ph.D. in biology, bioengineering, or related sciences 
• At least 5-6 years of experience with molecular biology techniques in a research or clinical laboratory
• Proficiency in R, Python, or an adjacent coding language
• Strong statistical analysis skills 
• Strong experience designing rigorous, well controlled studies in a molecular biology environment
• Experience with data presentation and technical report authoring
• Experience working with GMP, ISO, or equivalent environments, with strong knowledge of Quality Management Systems and practices.
• Excellent attention to detail
• Effective written and verbal communication skills
• Experience mentoring junior team members
• Possess logical troubleshooting skills

• Start-up experience
• Knowledge of medical genetics
• Experience in a cell-free DNA setting
• Experience with 6-sigma, Lean, JIT, TPS
• Experience with CLIA/CAP, 510K, PMA, and other regulatory requirements
• Experience with automation or clinical laboratory experience is a bonus

Unity Complete™ is the only non-invasive prenatal screen capable of assessing fetal risk for both common recessive conditions and aneuploidies from a single maternal blood sample.
Unity Confirm™ enables non-invasive confirmation for high-risk screening results through the capture of intact circulating fetal cells using BillionToOne’s Fetal Cell Capture™ Technology.
Our Northstar® liquid biopsy test uniquely combines treatment selection with real-time monitoring, giving oncologists unprecedented precision in cancer care.

From $0 to $400M+ annualized revenue run-rate in just 6 years. In 2025, we completed one of the most successful IPOs for a medical diagnostics company, building on nearly $400M in private funding,including our $130M Series D in 2024 and backed by world-class investors including Hummingbird, Adams Street Partners, Neuberger Berman, Baillie Gifford, and Premji Invest.

Forbes named us one of America's Best Startup Employers for 2025 and we're Great Place to Work certified, with 100% of our people willing to go the extra mile, even as we've scaled to over 700 employees.

Headquartered in Menlo Park with facilities in Union City, CA, and a new lab opening in Austin, TX in 2027, we're continuing to push the boundaries of what's possible in molecular diagnostics. We're just getting started.

Ready to help us change the world, one molecule at a time? Learn more at billiontoone.com