Do you want to join one of the fastest-growing molecular diagnostics companies to help transform prenatal and oncology diagnostics that can affect millions of patient lives?

BillionToOne (Y Combinator S17), ranked at the top 5% of Y Combinator companies with $200M+ in funding from prominent VC firms, has developed a DNA molecular counter that increases the cell-free DNA diagnostics resolution by over 1,000 fold. BillionToOne's first product, UNITY™ is the first and only prenatal screen that directly assesses the baby's risk for common and severe inherited disorders such as cystic fibrosis, spinal muscular atrophy (SMA), and hemoglobinopathies from a single tube of blood from the pregnant mother.

We are looking for a Sr. Development Scientist to join our growing superstar Process Engineering team in support of clinical patient testing in our high throughput CLIA lab. The Sr. Development Scientist will be responsible for (1) Creating and executing on a process development vision to support a rapidly scaling molecular diagnostic product line, (2) Identifying new technologies (chemistry, process, or other) to enhance product performance and/or improve COGS,  (3) Build upon our existing development systems to support increasing levels of Quality and Regulatory requirements without impeding innovation speed, and (4) Serving as a mentor for process engineers on the team. This role will enable an individual to flex their skills in product development and design, med device development, statistical analysis, experimental design, project planning, and data science (amongst many more).  This role will help to build upon the strong technology and execution found within BTO’s walls, and will help us pave the way for replicating our prenatal success in the oncology space. This is considered an onsite role and will require the majority of days to be spent in the office at either the Menlo Park or Union City sites.


  • Assess the current process and infrastructure against needs 12-18mo anticipated commercial demand. 
    • Build a sound development plan to bridge our current technology and processes.
    • Identify and anticipate the potential evolution of process bottlenecks during commercial growth and identify requirements for processes at key stages of growth. 
    • Identify and source new technologies (process changes, chemistry changes, instrumentation changes) for evaluation as potential solutions to future bottlenecks. 
    • Identify key areas for COGS improvements and create project proposals supported by in depth analyses.  
  • Build our development systems (Product Development Procedure, Design and Development Plans, etc) through close collaboration with R&D and PMO teams to satisfy and comply with ever increasing Quality requirements. 
    • Identify current development process deficiencies and build future-proofed solutions.
    • Identify potential regulatory requirements that we will face at major stages of company growth.  Create a strategy to build “quality-by design” infrastructure over time in a way that does not disrupt ability to innovate.
  • Mentor junior engineers and help to establish strong skills and industry best practices across the growing PE team. 
  • Plan studies in conjunction with RnD to identify CPPs, process tolerances, and failure modes during late stage product development. 
  • 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 within the clinical laboratory.


  • PhD in biological sciences, bioengineering, chemistry, chemical engineering or related discipline with extensive molecular biology lab experience
  • At least 3-4 years of direct experience developing commercial molecular diagnostics or similar technologies 
  • Experience working in regulated biotech industries (CLIA/CAP, FDA, EU, etc)
  • Proficiency in R or python
  • Strong Statistical Analysis skills 
  • Strong Experience designing rigorous, well controlled studies
  • 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
  • Experience with automation or clinical laboratory experience is a bonus


  • Start-up experience
  • Knowledge of medical genetics
  • Experience in a cell-free DNA setting
  • Experience with 6-sigma, Lean, JIT, TPS

Benefits And Perks:

  • Working with a team of ‘rockstars’ who bring out the best in everyone
  • Open, transparent culture that includes weekly Town Hall meetings
  • The ability to indirectly or directly change the lives of hundreds of thousand patients
  • Multiple medical benefit options; employee premiums paid 100% of select plans, dependents covered at 80%
  • Extremely generous Family Bonding Leave for new parents (16 weeks, paid at 100%)
  • Retirement savings program including a 4% Company match
  • Free daily on-site lunches provided from top eateries
  • Latest and greatest hardware (laptop, lab equipment, facilities)
  • A variety of perks on campus (state of the art gym, restaurant)
  • Free on-site EV charging (compatible with all EVs, including Tesla)

At BillionToOne, we are proud to offer a combination of a (1) base pay range (actual amount offered is based experience and salary/equity options split that the candidate chooses) (2) generous equity options offering, on top of (3) industry leading company benefits (free healthcare options, 401k match, very generous fully paid paternal leave etc.).

For this position, the base pay range is: $120,000 to $140,000 per year

BillionToOne is an equal opportunity employer. We do not discriminate on the basis of race, religion, color, national origin, gender, sexual orientation, age, marital status, veteran status, or disability status.

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