Automatic Light Intensity Modulation Using TNC-based Artificial Iris for Smart Contact Lens

In this paper we propose an artificial iris to tackle photophobia. This artificial iris is made with a twisted nematic cell (TNC) sandwiched between two linear polarizers. The light attenuation performance of a commercial TNC was compared with TNCs made from 5CB and E7 liquid crystals (LC) over a standard digital voltage range of 0 to 5V, automatically controlled by a light dependent resistor (LDR). The 5CB-based TNC exhibited lower threshold voltage than commercial TNC and entire light attenuation range around 3.3V, making it compatible with low-power electronic platforms. Maximum light attenuation equivalent to that of a ND32 filter was achieved. Utilizing polarizers in cross-plane or in-plane configuration, photophobia mitigation can be achieved in outdoor and indoor environment, while minimizing power consumption.