A low-power, high sensitivity, very low-cost light emitting diode (LED)-based device developed for low-cost sensor networks was modified with bromocresol green membrane to work as a solid-state pH sensor. In this approach, a reverse-biased LED functioning as a photodiode is coupled with a second LED configured in conventional emission mode. A simple timer circuit measures how long (in microseco...

This low cost visual stimulator was developed for use in small animal imaging. The stimulator uses a single tri-color LED for each eye and can output red, green, or blue light or any combination of the three. When all three LED colors are illuminated at the same time achromatic light is the output. The stimulator is almost entirely implemented in software with only minimal electronics. The LEDs...

Light-emitting diodes (LEDs) are widely used for data transmission in emerging optical wireless communications (OWC) systems. This paper analyzes the physical processes that limit bandwidth and cause nonlinearities light output of modern, high-efficiency LEDs. The carrier transport, as well storage, recombination, leakage active region appear to affect performance, but such purely physics-based...

the objective of this research was to develop a suitable method for color sorting of fruits. accordingly, a color-sorting system was designed and a prototype developed and then tested. this system includes an optic head which is designed to develop a reflection of the fruit. output of the head is then processed in an electronic control system which generates the appropriate signal for ejection ...

background and aims. today light cured composites are widely used. physical and mechanical properties of composites are related to the degree of conversion. light curing unit (lcu) is an important factor for composite polymerization. aim of this study is evaluation of composite resins hardness using halogen and led light curing units. materials and methods. in this study, 30 samples of filtek z...

BACKGROUND AND AIMS The aim of the present study was to compare the efficacy of quartz tungsten halogen (QTH) and light emitting diode (LED) curing lights on polymerization of resin composite. MATERIALS AND METHODS A hybrid resin composite was used to prepare samples which were cured using two QTH and ten LED light curing sources. Twelve groups, each containing ten samples, were prepared usin...