December 4, 2025 — A new biosensor made out of needles most commonly seen in dermatology clinics and medspas could make the fresh fish “smell test” seem antiquated.
For as long as humans have eaten fish, we’ve identified rot or spoilage by looking for a handful of physical signs. Cloudy eyes, bruised gills, and the unmistakable “fishy” smell are all signs that a piece of salmon might lead to gastric distress or worse. Though relatively effective, these observable signs take time to develop, time during which the fish may already be decomposing. A far more accurate method involves detecting faint traces of metabolic compounds that appear during the earliest stages of spoilage. While that is possible now, these methods typically require large, controlled laboratory settings.
Researchers at the American Chemical Society believe their new “microneedle based freshness sensors” device could make that process much more efficient. Detailed this week in the journal ACS Sensors, the team describes a small device made from an array of microneedles that inserts into a dead fish (or fillets) and continuously measures hypoxanthine (HX), a key compound closely associated with spoilage.