A low-cost LED-based multispectral capillaroscopy system for oximetry of the nailfold

Nailfold capillaroscopy is a technique for imaging the capillary bed in the finger nailfold, that is used in the diagnosis of scleroderma. Knowledge of the capillary oxygenation profile would be a substantial advantage in disease evaluation. A compact, low-cost LED-illuminated capillaroscopy system was conceived based on inexpensive parts and optical hardware. The system uses a compact Raspberry Pi to control a custom-designed LED ring light, with white-light LEDs interleaved with three narrowband LEDs, and a Raspberry Pi camera. Capillary visualisation and distinction of haemoglobin contrast is demonstrated, suggesting future promise for application of multispectral nailfold capillaroscopy in low-resource settings.