Fois 1

Optical power measurements were performed using a fiber-coupled spectrometer (QE65000, Ocean Optics, Inc.) connected to an integrating sphere (FOIS-1, Ocean Optics, Inc.) and calibrated using an NIST-traceable lamp (LS-1-CAL-INT, Ocean Optics, Inc.). The power output versus reference voltage ( $V_{\text{ref}}$ ) curve for each LED was characterized and used to optimize the optical position and alignment of LEDs and lenses. Optical power measurements of the overall system, as connected to an inverted fluorescence microscope, were also made by placing the integrating sphere on the sample stage immediately above the objective and measuring the intensity of each LED. Measurements taken at the stage represent the total illumination for each channel delivered to the target, allowing for correction of subsequent spectral images to a flat spectral response.

Silk hydrogel hemisphere lenses with 3 and 8 wt% silk solutions at a diameter of 7 mm were prepared and placed into an integrated sphere (Ocean Optics, FOIS-1). A spectrophotometer (Ocean Optics, Torus) connected integrating sphere and HL-3 VIS-NIR light source (Ocean Optics, HL-3 VIS-NIR) were used to measure the light extraction efficiency of the prepared samples. As control experiments, the reference light intensity was initially measured without any lens, and the extraction efficiency was calculated. Angle dependent measurements of silk hydrogel lenses were done using 360° rotating stage and spectrophotometer.

The optical absorption of the CSNP-PDMS fibre-optic films was measured across a wavelength range of 400–1600 nm. Broadband light from a halogen lamp (HL-2000-HP-FHSA, Ocean Optics, Dunedin, FL, USA) was delivered from the proximal end of a fibre and transmitted through the CSNP-PDMS coating at the distal end. Light transmitted through the coating was received in an integrating sphere (FOIS-1, Ocean Optics, USA) and measured with two spectrometers (Flame-T-VIS-NIR, Ocean Optics; 300–1000 nm and NIRQuest512, Ocean Optics, USA; 1000–1800 nm). A non-coated cleaved fibre of the same type was used as a reference and dark measurements were taken to correct for background light.

The current–voltage (I–V) characteristics of the µ-ILED was recorded with a source measurement unit (SMU, Keithley 2450) operating in the linear sweeping mode. The optical power was measured with an integration sphere (OceanOptics FOIS-1). The current consumption of the µ-ILED was measured with an Oscilloscope (Siglent SDS 1202X-E) measuring the voltage across a 10 Ω resistor in series with the µ-ILED. The wireless circuit uses a MOSFET (PMZ130UNE, Nexperia) to drive the µ-ILED with programmed predefined frequencies and duty cycles stored in the µC (ATTiny 13 A, Microchip Technology). Total current consumption of the device was measured using a benchtop power supply (1.8 V) with an Oscilloscope (Siglent SDS 1202X-E) recording the voltage drop across a 10 Ω resistor.

Light reflectance (Rf) and light transmittance (Tr) were measured on the fully expanded second leaves with a spectroradiometer (Ocean Optics USB2000+, Dunedin, FL, USA) in combination with two integrating spheres (FOIS-1, ISP-REF, Ocean Optics Inc., Dunedin, FL, USA). Light absorptance (Ab) was calculated as: Ab = 1 – (Rf + Tr). The diagram of the measuring apparatus is showed in Supplementary Figure 1.

The effect of irradiation was evaluated by measuring the transmission of white light through the irradiated area before and at various time points during the irradiation procedure. A broad-band source of white light (DT-Mini-2-GS, Micropack, Ocean Optics, Netherlands) was coupled to an optical fibre, the other end of which was placed in front of the lens. Light transmitted through the lens was collected by an integrating sphere (FOIS-1, Ocean Optics, Netherlands) that was coupled to a spectrometer using an optical fibre (USB4000, Ocean Optics, Netherlands). Transmission was calculated as the ratio between transmitted and incident light after correction for background levels of light as described previously [14 (link)]. To correct for fluctuations in the intensity of the light source all measurements were calibrated by setting the transmission from 650 to 700 nm to 100% since transmission at this band of the spectrum changes little with age [15 (link)]. For the evaluation of the effect of photobleaching the attention was focused on the transmission of blue light (450–490 nm) since the largest age-related changes in transmission takes place in the blue wavelength region [14 (link)]. Blue light lens transmission was evaluated as the area under curve of transmission from 450 to 490 nm.