Multimodal LLM-Assisted Diagnosis of Cryptic Failure Modes in High-Throughput Experimentation: A Case Study in Gold Nanorod Synthesis
Year: 2026
Type: preprint
Abstract: Self-driving labs typically optimize experiments within a predefined design space. Yet high-throughput campaigns can fail for reasons outside this design space, in-cluding reagent state, stock solution quality, and handling history. Here, we present a case study of a five-plate high-throughput gold nanorod synthesis campaign in which a multimodal large language model (LLM) helped diagnose such cryptic failure modes. We used low-cost camera images for rapid assessment of seed and synthesis state, with UV–vis spectroscopy when the images were insufficient for failure diagnosis. The campaign included an abnormal seed batch, a visually plausible synthesis with hidden spectroscopic defects, and a plate-wide failed synthesis in which most wells showed weak spectra with a strong rise toward the near-infrared. In response, the LLM intervened by questioning the seed preparation step and reagent handling instead of optimizing the screened concentrations of silver nitrate and ascorbic acid. To quantify recovery, we defined a UV–vis spectral roughness metric based on local spectral interpolation across the synthesis grid. The final synthesis had the lowest roughness, Rspec = 0.636 compared with ∼ 0.772 for earlier successful runs, and the highest median longitudinal-window absorbance. Our results show the potential of multimodal LLMs upstream of autonomous optimization in self-driving labs to identify when an experiment has failed for reasons outside the nominal design space and when additional characterization is needed before optimization should continue.
Source: ChemRxiv
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7213979959