Steven R. Daly

Novel LED array used for photodynamic therapy (PDT)

Light Sciences Corporation has developed a novel LED array that was designed and manufactured to treat large bulky tumors. We describe our LED design process, culminating in the manufacture of a flexible silicone catheter currently under investigation in a Phase 1 clinical trial. The performance characteristics of the wire-bonded die to a flexible polyimide substrate forming a linear array are discussed. The LED array consists of 100 die arranged asymmetrically on the substrate with 50 LEDs on either side producing up to 60mW total optical power at 38°C (500mA) over a spectral bandwidth 645-670nm FWHM. The LEDs are encapsulated within biocompatible silicon for interstitial placement within the treatment tissue. The effect of time, temperature and humidity on the device performance was investigated. Optical power ranged from −2.5% to +0.5% of the normalized original power over 50 hours in 100% RH within the control group. Over a temperature range of 35°C to 50°C the optical power decreased at a rate of 0.56% per °C. Preliminary non-clinical experiments carried out in normal swine muscle demonstrate a significant treatment zone and are consistent with threshold models for photodynamic effect.