Flexible computational photodetectors for self-powered activity sensing

Abstract

Conventional vision-based systems, such as cameras, have demonstrated their enormous versatility in sensing human activities and developing interactive environments. However, these systems have long been criticized for incurring privacy, power, and latency issues due to their underlying structure of pixel-wise analog signal acquisition, computation, and communication. In this research, we overcome these limitations by introducing in-sensor analog computation through the distribution of interconnected photodetectors in space, having a weighted responsivity, to create what we call a computational photodetector. Computational photodetectors can be used to extract mid-level vision features as a single continuous analog signal measured via a two-pin connection. We develop computational photodetectors using thin and flexible low-noise organic photodiode arrays coupled with a self-powered wireless system to demonstrate a set of designs that capture position, orientation, direction, speed, and identification information, in a range of applications from explicit interactions on everyday surfaces to implicit activity detection.

Organic photodiodes: device engineering and applications

“…Additionally, various system prototypes of OPDs have been built to seek potential applications in wearable health sensing devices, optical imagers, spectrometers, light communication systems, etc. [16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Due to inherent mechanical flexibility and process compatibility with low Young's modulus plastic substrates, one promising application of OPDs is in skin-conformal optical sensors for wearable health monitoring and medical diagnostics (e.g., photoplethysmography (PPG) and cardiovascular sensing) with minimal invasiveness [15].…”

Interface Engineering for High-Performance and Stable Hybrid Perovskite Shadow-Effect Energy Generator

“…Moreover, taking advantage of the power generation ability of SEG devices with the coexistence of shadowed and illuminated portions, the feasibility of using SEG devices for self-powered photodetectors could be envisaged. Typically, the photodetectors can be applied to motion sensors that can recognize human physical activities has many potential applications in various fields such as people and traffic counter, and rehabilitation. , In contrast to state-of-the-art motion sensors that generally require an external power supply (e.g., battery) for powering the associated electronic circuitry, the sensor system based on SEG devices can be operated in self-powered mode. To validate the concept, we preliminarily examined the photoresponse characteristic of the SEG devices (device G) measured under illumination at a near-infrared wavelength (820 nm, light intensity = 13.5 mW cm –2 ) without any external bias (i.e., self-powered operation).…”

Stabilizing Non‐Fullerene Organic Photodiodes through Interface Engineering Enabled by a Tin Ion‐Chelated Polymer

“…Organic photodetectors are emerging as a promising alternative to the traditional inorganic counterparts in optical detection technology, thanks to their remarkable advantages, [1][2][3][4] and thereby DOI: 10.1002/advs.202302976 have potential applications in health monitoring, biomedical imaging, artificial vision, and so on. [5][6][7][8][9] In general, the state-of-theart organic photodetector is diode-type (that is organic photodiode, OPD), which consists of a bulk-heterojunction (BHJ) active layer that is in the form of phase-separated blends of electron donor and electron acceptor.…”