# Conformal Retinal Image Sensor Based on Electrochemically Exfoliated MoS2 Nanosheets

## TL;DR

A flexible, conformal retinal image sensor using MoS2 nanosheets is developed for applications in prosthetics and sensing.

## Contribution

A kirigami-based fabrication method enables high-performance conformal photodetectors using MoS2 on flexible substrates.

## Key findings

- The device achieves a responsivity of 247.9 A/W and detectivity of 6.16 × 10¹¹ Jones.
- The sensor array successfully recognizes shapes on a curved surface with 180 pixels.
- The kirigami strategy allows seamless integration on spherical surfaces without wrinkles.

## Abstract

Retina-like photoimaging devices with features such as a wide-field-of-view and high spatial resolution have wide application prospects in retinal prosthetics and remote sensing. However, the fabrication of flexible and conformal surfaces is hindered by the incompatible microfabrication processes of traditional rigid, silicon-based substrates. A kirigami strategy for hemispherical surface assembly is proposed to construct a MoS2-based retina-like photodetector array. The device is first fabricated on a flat polyimide (PI) substrate and then tailored using a laser. By approximating the spherical surface using planar sectors, the laser-cut PI film can tightly adhere to the PDMS spherical shell without significant wrinkles. The responsivity and specific detectivity of our conformal photodetector can reach as high as 247.9 A/W and 6.16 × 1011 Jones, respectively. The array integrates 180 pixels on a spherical crown with a radius of 11 mm, and a hollow letter “T” is successfully recognized. Comprehensive experimental results in this work reveal the utility of our device for photoelectric detection and imaging. We believe that our work provides a new methodology for the exploitation of 2D material-based retinal image sensors.