The science behind Em-Lux
Em-Lux measures the fluorescence lifetime of NADH, a coenzyme in cellular energy metabolism, without touching the cells. It is designed to assess embryos, and egg assessment is in development on the same instrument. This page covers the biology, what Em-Lux measures, the published research and both applications.
The embryo and the inner cell mass
By day five, an embryo is a blastocyst. Its outer layer, the trophectoderm, forms the placenta. The inner cell mass becomes the fetus. A PGT-A biopsy samples the outer layer; Em-Lux images the inner cell mass without contact.
Within the inner cell mass, the epiblast cells become the fetus; the primitive endoderm forms the yolk sac. Inside each cell, mitochondria produce energy for development. NADH, a coenzyme in this process, fluoresces naturally.
What Em-Lux measures
NADH fluoresces naturally. Its fluorescence lifetime is different when it is bound to enzymes than when it is free, which reflects how the cell is producing energy. Nothing is added to the sample.
Additional molecules, such as FAD, are on our development roadmap.
Published research on FLIM in embryos
Culture stress
Embryos under nutrient or osmotic stress separate from controls.
Glycolysis
Blocking key metabolic enzymes in mouse oocytes and embryos shifts the lifetime signature; the authors reported that imaging did not significantly impair mouse embryo development (Sanchez et al., 2019).
Development
Published work reports signatures that change in a consistent way from zygote to blastocyst.
Ploidy
FLIM found significant metabolic differences between euploid and aneuploid human blastocysts (Shah et al., 2022).
Summaries of published studies. See References below.
One instrument, two points in the IVF cycle
Em-Lux measures the same metabolic signal at two decision points: before an egg is frozen or fertilized, and before an embryo is transferred or frozen. Embryo assessment is the focus of our current research. Egg assessment is in our development pipeline.
- 01Egg retrievalMature eggs are collected.
- 02Egg assessmentMetabolic read of each egg before freezing or fertilization. In development.
- 03FertilizationIVF or ICSI.
- 04CultureDays 1 to 5 in the incubator.
- 05Embryo assessmentInner cell mass scan and EMMI score on day 5 or 6. Investigational.
- 06Transfer or freezeThe clinical team decides.
Embryo assessment
INVESTIGATIONAL ยท IN CLINICAL RESEARCHEm-Lux images each embryo at the blastocyst stage and measures metabolism in the inner cell mass, the region that becomes the fetus. EMMI combines that measurement with morphology and patient data to report a viability score for each embryo, and ranks the embryos in the dish.
- When
- Day 5 or 6 blastocyst, before transfer or freezing
- Where
- Inner cell mass, imaged without contact
- Signal
- NADH fluorescence lifetime and bound and free fractions
- Combined with
- Morphology and patient data, in EMMI
- Output
- A viability score per embryo and a ranking within the cohort
- Scan time
- About 1 minute per embryo
Decisions it is designed to inform
Which embryo to transfer first
A ranking of the embryos in a cohort to support the embryologist's choice. The final decision stays with the clinical team.
Which embryos to freeze
Additional information when deciding which embryos to vitrify for later use.
A view alongside PGT-A
A metabolic measure that needs no biopsy, designed to be used with existing methods rather than replace them.
Research basis: published FLIM studies in mouse and human embryos, including metabolic differences between euploid and aneuploid human blastocysts (Shah et al., 2022), and Noor data presented at PCRS 2026 (Nel-Themaat et al.).
Egg assessment
IN DEVELOPMENT PIPELINEThere is no standard objective method today to assess an egg before it is frozen or fertilized. Em-Lux is being developed to measure the same metabolic signal in mature eggs, on the same instrument used for embryos.
- When
- Mature (metaphase II) eggs after retrieval, before freezing or fertilization
- Where
- The egg cytoplasm, where mitochondria produce energy
- Signal
- NADH fluorescence lifetime, the same signal used for embryos
- Published basis
- NADH lifetime has been measured in oocytes and in the cumulus cells around them (Sanchez et al., 2019; Venturas et al., 2023)
- Output
- An egg-level metabolic measure; scoring is in development
Potential applications
Egg freezing
Information on egg quality when patients decide how many eggs to bank.
Choosing eggs to fertilize
A way to prioritize eggs when not all of them can be used.
Donor eggs and egg banks
Designed to give a shared measure across donors, clinics and banks.
One instrument
Eggs and embryos assessed on the same system in the lab.
Embryos and eggs at a glance
| Embryo assessment | Egg assessment | |
|---|---|---|
| Stage | Day 5 or 6 blastocyst | Mature egg, after retrieval |
| Region measured | Inner cell mass | Cytoplasm |
| Signal | NADH fluorescence lifetime | NADH fluorescence lifetime |
| Contact with the cell | None; light only | None; light only |
| Decision it is designed to inform | Transfer order and which embryos to freeze | Which eggs to freeze or fertilize |
| AI output | EMMI viability score and ranking | In development |
| Status | Investigational; in clinical research | In development pipeline |
Both applications are investigational and not FDA cleared.
From measurement to a score
See how Em-Lux captures this signal in the lab, and how EMMI combines it with morphology and patient factors.
References (9)
- Nel-Themaat L, Azartash K, Menjivar N, Hellriegel C. A novel non-invasive selection platform for assessing embryo metabolic state and ploidy. PCRS 2026.
- Shah JS, Venturas M, Sanchez TH, Penzias AS, Needleman DJ, Sakkas D. Fluorescence lifetime imaging microscopy (FLIM) detects differences in metabolic signatures between euploid and aneuploid human blastocysts. Hum Reprod 2022;37(3):400-410.
- Sanchez T, Venturas M, Aghvami SA, et al. Combined noninvasive metabolic and spindle imaging as potential tools for embryo and oocyte assessment. Hum Reprod 2019.
- Venturas M, et al. Noninvasive metabolic profiling of cumulus cells, oocytes, and embryos via fluorescence lifetime imaging microscopy. Hum Reprod 2023.
- Ma N, et al. Label-free assessment of pre-implantation embryo quality by the FLIM-phasor approach. Sci Rep 2019.
- Skala MC, et al. In vivo multiphoton microscopy of NADH and FAD redox states, fluorescence lifetimes, and cellular morphology. PNAS 2007.
- Blacker TS, et al. Separating NADH and NADPH fluorescence in live cells and tissues using FLIM. Nat Commun 2014.
- Leese HJ. Metabolism of the preimplantation embryo: 40 years on. Reproduction 2012.
- Cao R, et al. Multiphoton FLIM imaging of NAD(P)H and FAD with one excitation wavelength. J Biomed Opt 2020.