Figure 2. Electrical, optical, mechanical, and thermal properties.

A) Current-Voltage-Light output characteristics. B) Emission spectra associated with operation of devices built with different μ-ILEDs. C) Normalized light optical power as a function time after immersion of devices in warm saline solutions with temperatures of 37, 60 and 90 °C. D, E) Normalized light optical as a function of extension of the serpentine interconnect to the injectable needle and of the bending radius of the body of the device, respectively. F) Change in temperature adjacent to an operating μ-ILED (T: Theoretical, for the case of brain tissue; E: Experimental, for the case of a hydrogel) as a function of duty cycle of operation at different peak output powers (10, 20 and 50 mW/mm²). G) Current output from a photodiode placed adjacent to a μ-ILED operating at different pulse frequencies (5, 10 and 20 Hz), for a fixed duration of 20 ms. The rise and fall times are ~0.1 ms.