Engineer, Rewarming Systems

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 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.

120000 - 145000 USD a year

Benefits:

• Generous medical, dental and vision insurance coverage

• Flexible time off and paid holidays

• Competitive compensation package, including salary and equity

• Access to a 401(k) retirement savings plan

• FSA and commuter benefits

• Daily lunch and dinners, plus a variety of snacks

• Monthly learning stipend

• On-site fitness center

• Quarterly team social budget