The LED chips were arrayed in a foldable ring configuration,12,13 with an inner diameter of 55 mm and an outer diameter of 65 mm. It was composed of surface mount white light LEDs (5050-A66, SURTEK CO., LTD, Hsin-Chu, Taiwan) of size .14,15 Transparent medical grade isolation tape (3M™ Transpore™ Clear Porous Plastic Hypo-Allergenic Surgical Tape) was used to secure the LED assembly. The foldable design of the ring assembly allowed its easy insertion through the wound retractor into the thoracic cavity.16,17 It can be attached to the rubber ring of the retractor inside the chest cavity, as shown in Fig. 2. The module was powered with overheat protection to prevent accidental burning of the LED chips or nearby tissues in direct contact, with the maximum temperature set at 40°C. The powering control module consisted of an AC to DC converter (A1-111612A, Jin-Hua Electronic Co., Taipei, Taiwan), a regulator (UA7815, Texas Instrument Corp., Dallas, Texas), an overheat detector, an alarm circuit, a buzzer (AX1203D, Advanced Acoustic Technology Corp., Taipei, Taiwan) and a 3 mm dip red light LED for displaying warning signal (W-Great Enterprise Co., Kaohsiung, Taiwan). When the voltage reached the preset value due to elevated temperature, the buzzer and the red light LEDs were activated to remind the operators.