Do you want to join one of the fastest-growing molecular diagnostics startups and develop products that can affect the lives of millions?

BillionToOne, ranked at the top 5% of Y Combinator companies with $300M+ in funding from prominent VC firms, has developed a DNA molecular counter that increases cfDNA diagnostic resolution by over 1,000 fold. BillionToOne's first product, UNITY™ is the first and only non-invasive prenatal test that can directly screen an unborn baby and assess its risk for common and severe recessive gene disorders and chromosomal abnormalities, as well as fetal sex and fetal antigens, from a single tube of blood from the pregnant mother without paternal testing.

In 2023, BillionToOne launched two liquid biopsy products that will markedly improve oncology treatment and care. With Northstar Select™, clinicians will be able to select cancer therapies that will be most effective to each patient based on their individual genetic makeup. Northstar Response™ will enable clinicians to monitor a patient’s early response to these cancer therapies, by measuring minute changes in their ctDNA, which can reduce ineffective treatments and unwanted toxicity, lower costs, and substantially improve clinical outcomes.

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, med device development, 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, and will help us pave the way for replicating our prenatal success in the oncology space. 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, 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. 
  • 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. 
  • 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. 
  • Support high throughput CLIA lab through troubleshooting instrumentation and re-qualifying instrumentation back into clinical use
  • Identify root causes for process and instrument errors and develop long term solutions.


  • Bachelor’s or Master’s (preferred) degree 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 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
  • Experience with CLIA/CAP, 510K, PMA, and other regulatory requirements

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 thousands 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 parental leave etc.).

For this position, the base pay range is: $120,000-$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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