---
title: 'Engineer, Rewarming Systems at Until'
canonical: 'https://feeny.ai/job/engineer-rewarming-systems-until-san-francisco-tswax2n4d0ca'
type: 'job'
last_seen: '2026-11-02'
---

# Engineer, Rewarming Systems at Until

- **Company:** Until
- **Location:** San Francisco, CA
- **Compensation:** $120k–$145k
- **Employment:** full-time
- **Work type:** onsite
- **Posted:** 2026-10-22
- **Last confirmed live:** 2026-11-02
- **Apply:** https://jobs.lever.co/until/e6a9408c-00ef-4382-8d22-44ff7d8d90bd

## Job description

## About the Company

Until is a moonshot company building a “pause button” for biology. Our near-term focus is organ-scale reversible cryopreservation: preserving donated organs at subzero temperatures without ice formation, then rewarming them uniformly for transplant. By solving this grand challenge, we’re laying the foundation for whole-body reversible cryopreservation, giving patients a bridge to future cures. To achieve our goal, we are assembling an interdisciplinary team to develop perfusion systems, cryoprotectant formulations, and vitrification and rewarming hardware. We envision a future where no transplantable organ is lost to logistics, and no terminal diagnosis is final because patients can safely wait for future medicine to arrive.

## About the Role

One of the key unsolved challenges in cryopreservation is the rewarming problem: how do we rapidly and uniformly rewarm whole organs and, ultimately, whole bodies to restart cryopreserved biology? Our high-power rewarming platform generates tens of kA/m at MHz frequencies, but that power only matters if it deposits the right amount of heat in the right places inside a vitrified organ. That happens at the interface between the platform and the biological sample, and this role owns it.

We are looking for fast-moving, hands-on engineers and physicists with strong fundamentals, high autonomy, and a desire to build technology that feels impossible until it works. This role is for someone who is as comfortable deriving a back-of-the-envelope model from electromagnetics, fluid dynamics, and heat transfer as they are building hardware and running experiments with real organs in the lab.

## What You'd Do

- Design, build, and operate the hardware and software linking the rewarming system and the organ: holders, fluidic circuits, sensing, control, and data acquisition.

- Run experiments on holder designs and cooling and rewarming protocols alongside the organ and cryobiology teams.

- Reason from first principles, using electromagnetics, heat transfer, imaging and measurement data, to model nanoparticle distribution and heating uniformity, then refine hardware and protocols.

- Develop sensing, control, interlock, and logging software for field profiles and temperature feedback.

- Learn quickly, take ownership of ambiguous problems, and contribute across the full rewarming hardware stack.

## About You

- 3+ years of hands-on engineering experience (student teams count), and a project you can walk us through in depth: the reasoning and where your first model was wrong.

- Strong command of electromagnetics, heat transfer, and fluid dynamics.

- Mechanical design and fabrication experience (CAD, rapid prototyping, 3D printing, etc.).

- Circuit design experience from protoboard to PCB, plus building and debugging sensors, data acquisition, and control systems.

- Proficient in object-oriented programming in Python and/or C++.

- Eager to work closely with biologists (no biology background required).

- Desire to join a small, fast-paced team on an excellent adventure.

As an equal opportunity employer, Until is committed to providing employment opportunities to all individuals. All applicants for positions at Until will be treated without regard to race, color, ethnicity, religion, sex, gender, gender identity and expression, sexual orientation, national origin, disability, age, marital status, veteran status, pregnancy, or any other basis prohibited by applicable law.

## About Until

## Company Overview
- **One-liner**: Until is building reversible cryopreservation technology to bank whole human organs, extending viability from hours to weeks or months, with the long-term goal of whole-body cryopreservation.
- **Entity Type**: Private (Privately Held)
- **Headquarters**: San Francisco, California, United States
- **Founded**: 2025
- **Founders**: Laura Deming (CEO, Co-founder) and Hunter Davis Ozawa (CSO, Co-founder)

## Core Business
- Primary industry/industries: Biotechnology Research, Cryopreservation, Organ Preservation, Hibernation Science
- Target customers: Organ procurement organizations, transplant hospitals, and ultimately patients waiting for organ transplants (B2B with healthcare institutions)
- Mission or purpose statement: "Pressing pause on biological time, for those who need it most." The company aims to solve the organ procurement and matching problem by making donated organs last long enough to reach any patient in need.

## Products & Services
- **Reversible Cryopreservation for Whole Organs**: A technology that cools organs to -130°C using biocompatible cryoprotectants, then rewarms them without damage, turning hours of viability into weeks or months.
- **Cryoprotectant Discovery Engine**: A platform combining physics simulations and machine learning to screen over 250,000 candidate molecules for cryoprotective formulations that stay within a "Biocompatibility Budget" – preventing ice formation without harming cells.
- **Hibernation Research**: Exploratory work on inducing reversible metabolic arrest (hibernation-like states) in organisms, with potential applications in organ preservation and future whole-body suspension.

## Market Standing
- **Valuation/Market Cap**: Not publicly available (private company, founded 2025)
- **Key Metric**: Total Funding – Not disclosed; headcount of 53 employees (as of early 2026) with 9.5% monthly growth and 29 active job postings.
- **Notable Investors/Partners**: Not publicly listed. The company is co-founded by Laura Deming, a noted longevity and biotech investor (founder of the Longevity Fund), which may signal strong investor connections.
- **Growth Signals**: Rapid hiring (29 open roles for a 53-person team, +31.8% quarterly job posting growth), high-throughput screening scale (2,903 formulations tested in Q2 2026 alone), and public progress on cryoprotectant discovery.

## Competitive Advantages
- **Combination of Physics Simulation and ML**: Their discovery engine screens millions of molecules in silico before wet-lab validation, dramatically accelerating cryoprotectant development.
- **Biocompatibility Budget Framework**: A novel approach that distributes cryoprotectant toxicity across multiple mechanisms, avoiding the single-dose toxicity that has stymied the field for 50 years.
- **Focus on Whole Organs (not just cells)**: Extending cryopreservation from small samples (IVF, stem cells) to whole human organs – a much harder problem with massive clinical impact.
- **Talent Philosophy**: "Proof of work" culture that hires for demonstrated ability over credentials, with fast promotion for those who earn it.

## Strategic Focus
- **Immediate**: Scale up cryoprotectant discovery and validation to achieve reversible cryopreservation of a whole human organ (likely a kidney or heart) within the next few years.
- **Medium-term**: De-risk and build the foundation for whole-body reversible cryopreservation, enabling "a bridge to future cures" for patients with currently incurable conditions.
- **Talent Acquisition**: Aggressively hiring scientists, engineers, and operations staff across physics, biology, chemistry, and engineering disciplines to accelerate R&D.

## Why Work Here
- **Work Environment**: On-site in San Francisco (HQ). The work spans "the edge of physics, biology, and engineering" – from quantum-level simulations to handling real organs. Culture emphasizes "hard problems", rigor, and speed.
- **Culture**: Flat hierarchy, promotion on merit, "proof of work" over credentials. Team includes people from top universities and self-taught scientists alike.
- **Benefits**: Comprehensive medical/dental/vision, 401(k) via Guideline, unlimited PTO, paid parental and disability leave, on-site fitness center, catered lunch and dinner, plus snacks.
- **Engineering & Science**: Opportunity to work on cutting-edge cryobiology, nanotech, polymer chemistry, and high-throughput automation. The company uses AI tools in hiring but makes final human decisions.

## Sources
1. [untillabs.com/careers](https://www.untillabs.com/careers)
2. [untillabs.com](https://untillabs.com/)
3. [untillabs.com/our-team](https://www.untillabs.com/our-team)
4. [builtin.com/company/until-labs](https://builtin.com/company/until-labs)
5. [jobs.lever.co/until](https://jobs.lever.co/until)

## Other roles at Until

- [Scientist/Senior Scientist, High-Throughput Screening](https://feeny.ai/job/scientist-senior-scientist-high-throughput-screening-until-san-francisco-e4xp9jk9s8wk) — San Francisco, CA
- [Veterinarian/Anesthesiologist](https://feeny.ai/job/veterinarian-anesthesiologist-until-san-francisco-jmezz5c9n59y) — San Francisco, CA
- [Strategic Finance Manager](https://feeny.ai/job/strategic-finance-manager-until-san-francisco-ad3nnxtst866) — San Francisco, CA
- [Sensing & Instrumentation Engineer](https://feeny.ai/job/sensing-instrumentation-engineer-until-san-francisco-g88j5wvqkyya) — San Francisco, CA
- [Lab Technician](https://feeny.ai/job/lab-technician-until-san-francisco-85pf3399p5m3) — San Francisco, CA
- [Senior / Staff Power Electronics Engineer](https://feeny.ai/job/senior-staff-power-electronics-engineer-until-san-francisco-5y9bjz922v89) — San Francisco, CA
- [Senior Scientist, Cardiac Preservation (Organ Perfusion)](https://feeny.ai/job/senior-scientist-cardiac-preservation-organ-perfusion-until-san-francisco-b452rfthhqkp) — San Francisco, CA
- [Research Associate (Organ Perfusion)](https://feeny.ai/job/research-associate-organ-perfusion-until-san-francisco-0b1srem75ztf) — San Francisco, CA
- [Head of Legal](https://feeny.ai/job/head-of-legal-until-san-francisco-a15h6wha3f21) — San Francisco, CA
- [Research Associate, Hibernation](https://feeny.ai/job/research-associate-hibernation-until-san-francisco-a9jr1rkbe83f) — San Francisco, CA