Lead Chemist (oil and surfactants)

We are looking for a hands-on Oil & Surfactant Lead Chemist to develop the fluidic operating system of Rivercell's platform and make it compatible with robust, high-throughput cell biology. You will own the selection and optimization of carrier oils, surfactants, aqueous formulations, and operating protocols that enable reliable droplet manipulation while preserving cell viability and biological function. You will bridge microfluidics, interfacial physical chemistry, and cell biology.

You will work hand-in-hand with our device integration lead, surface engineering scientist, thin-film materials engineer, characterization engineer, assembly team, and cell biology team. You will also collaborate with an interdisciplinary group spanning genetic engineering, AI and software, bio-laboratory automation, optics, and electronics, and be an integral part of an ambitious startup project from its inception.

Select and optimize carrier oils based on viscosity, dielectric properties, conductivity, optical transparency, volatility, gas permeability, chemical stability, and biological compatibility Select and optimize surfactants and interfacial additives to control droplet stability, coalescence, wetting, pinning, protein adsorption, and cell adhesion Build formulation maps linking oil and surfactant composition, concentration, temperature, droplet size, waveform, frequency, and actuation performance Evaluate formulations for cell viability, proliferation, morphology, membrane integrity, phenotype, and assay performance over relevant experimental durations

Adapt the fluidic system to complex media containing salts, serum, proteins, extracellular matrices, drugs, dyes, nucleic acids, and suspended cells Characterize interfacial tension, viscosity, dynamic wetting, emulsion stability, evaporation, gas exchange, and the partitioning of water, proteins, and small molecules Minimize cross-talk, reagent loss, fouling, osmotic drift, unwanted extraction, bubble formation, and contamination between droplets Define chip priming, loading, filling, bubble-removal, sample-recovery, cleaning, storage, and preconditioning procedures

Design diagnostic experiments and translate results into formulation specifications, operating windows, quality controls, and standardized protocols Opportunity to work on a cutting-edge project in the field of biotech Opportunity to join an ambitious team and impactful startup among the first employees Competitive salary and equity package Exciting opportunities for personal and professional growth within the team

a PhD in microfluidics, chemical engineering, physical chemistry, soft matter, bioengineering, biophysics, or a related field.

• You have 4+ years of hands-on experience developing microfluidic systems, multiphase formulations, emulsions, or droplet-based assays.
• You have a strong understanding of wetting, capillarity, interfacial tension, surfactants, emulsions, mass transfer, and transport phenomena.
• You can connect fluid properties and interfacial mechanisms to measurable device performance and biological outcomes.
• You are comfortable exploring multidimensional formulation spaces and drawing practical conclusions from imperfect data.
• You are autonomous, committed, enthusiastic, and comfortable working with a can-do, creative, and challenging mindset.
• You are rigorous in experimental documentation, formulation traceability, data interpretation, and communication of uncertainty.
• You have excellent communication skills and are fluent in English; professional proficiency in French is helpful but not required.
• You have previous experience or knowledge in one or more of the following areas: Droplet microfluidics, digital microfluidics, electrowetting, emulsions, or lab-on-a-chip systems Fluorinated, silicone, or hydrocarbon oils; fluorosurfactants, non-ionic surfactants, block copolymers, or custom amphiphilic formulations Cell culture, cell-based assays, organoids, primary cells, immune cells, or other sensitive biological samples Tensiometry, contact-angle measurements, microscopy, particle tracking, or high-speed imaging

Design of experiments, formulation screening, statistical analysis, automated experimentation, or process development Please let us know in your application if you specifically have experience with one or several of the following: Optimizing oil and surfactant systems for mammalian cell culture or long-duration biological experiments Quantifying partitioning, adsorption, reagent loss, cross-talk, or small-molecule transport in droplet systems Working with fluorinated oils and biocompatible fluorosurfactants, including protein- or polymer-based surfactants Electrowetting and the influence of conductivity, permittivity, viscosity, and waveform

Transferring fluid formulations and priming, filling, bubble-management, recovery, and cleaning protocols into repeatable operation

Throughout the recruiting process, you will meet 4 to 6 team members of Rivercell. Introductory call (up to 30mn, videocall) Technical interview (up to 90mn) Performance interview (up to 90mn, in person) Culture interview (up to 60mn, in person)