Nano gold powders are generally formulated into gold ink or gold paste to fabricate sensor electrodes and sensing sensitive layers. Colloidal gold (liquid‑phase nano‑gold) is widely applied in immunological rapid-test strips.
Core Advantages:
1. Excellent chemical stability
2. High specific surface area and catalytic activity
3. Highly modifiable surface
4. Unique LSPR (Localized Surface Plasmon Resonance) optical property
5. Good biocompatibility and low cytotoxicity
Drawback: Gold has high material cost. Mostly it is used for electrode modification or minor catalytic doping.
Marketoriented Applications
Immunological Rapid‑Detection Assays (Largest mature market, colloidal gold / liquid‑phase nano‑gold)
‑ Applications: Mass‑produced colloidal‑gold test strips for pregnancy tests, antigen rapid tests, infectious‑disease screening, drug testing and food‑safety inspection.
‑ Form: Colloidal gold (water‑dispersed nano‑gold particles). Dry powder is not used directly; dry nano‑gold powder is dispersed to prepare colloidal gold.
Electrochemical Sensors (printed electrodes, chip‑based sensors)
‑ Industrial & environmental electrochemical detection chips: Screen‑printed nano‑gold electrodes for heavy‑metal and environmental‑pollutant water testing. Instrument manufacturers purchase gold paste in bulk for printed‑electrode fabrication; this technology is commercially available.
‑ Medical POCT electrochemical sensor chips: In‑vitro diagnostic chips with nano‑gold‑modified electrodes for improved sensitivity. Some portable detection devices are produced in small batches, while many products are still under medical‑device verification.
MEMS / Thick‑Film Gas Sensors (doping modification, not main material)
Small amounts of nano‑gold powder are doped into metal‑oxide gas‑sensing materials (e.g. SnO₂) as catalytic promoters, to boost sensitivity, lower operating temperature and improve selectivity. It has achieved small‑volume commercialization for industrial gas sensors. Nano‑gold acts as a minor‑fraction dopant rather than the primary sensing material.
R&D / Small‑Batch Stage
SERS (Surface‑Enhanced Raman Scattering) sensors; microfluidic biochips; flexible sensors; breath‑analysis sensors, etc.