Key Takeaways & Executive Findings
- •• • The event-driven sensor achieves a gesture recognition accuracy exceeding 92.5%, enabling reliable UAV control in real-time HMI scenarios. • • In a simulated 10-second scene at 1920×1080 resolution, the event-based sensor generates an average file size of 7.5 MB, compared to 14.8 MB for a frame-based sensor, representing a 49.3% reduction in data redundancy. • • The device architecture (Sb-doped TiO2/QDs/PEDOT:PSS) is solution-processed and two-terminal, simplifying fabrication and potentially lowering production costs compared to complex DVS circuits. • • The hybrid HMI system combines event-driven sensing for low-latency gesture control with frame-based sensing for high-precision gaze control, demonstrating a scalable strategy for multi-stage tasks.
Abstract
Contactless human-machine interaction (HMI) is rapidly evolving, yet it remains constrained by the latency, redundancy, and power consumption inherent in conventional frame-based vision sensors. While bio-inspired event-driven sensors offer a low-power alternative, existing architectures are often complex or fail to accurately encode the magnitude of light intensity changes. Herein, we report a solution-processed, two-terminal event-driven sensory device based on CuIn(Se,S)2 colloidal quantum dots (QDs) integrated with an Sb-doped TiO2 layer. Unlike traditional dynamic vision sensors (DVS), this device exhibits a transient photoresponse that encodes both the polarity and the magnitude of light intensity variations into the output current amplitude. This preservation of magnitude information significantly enhances the feature extraction capability, leading to faster convergence and superior clustering performance in gesture recognition. Based on these unique optoelectronic properties, we constructed a hierarchical HMI system that synergizes the strengths of event-based and frame-based sensing. The system utilizes the event-driven sensor for low-latency gesture control of an unmanned aerial vehicle (UAV) and a frame-based sensor for high-precision gaze control of an unmanned ground vehicle (UGV). The proposed system achieves a gesture recognition accuracy of more than 92.5% while substantially reducing data redundancy, offering a promising strategy for efficient, robust, and low-cost intelligent interaction systems.
1. Introduction
Conventional frame-based image sensors respond to absolute light intensity, generating signals proportional to illumination. While they capture static scenes accurately, they suffer from high latency and significant data redundancy, limiting their use in real-time, low-power HMI applications. Bio-inspired event-driven sensors, which respond only to changes in light intensity, offer lower latency and reduced data overhead. However, existing event-driven architectures are often complex, and simpler designs like dynamic vision sensors (DVS) fail to encode the magnitude of intensity changes, compromising feature extraction and recognition accuracy.
This work addresses these bottlenecks by introducing a two-terminal, solution-processed photodetector based on CuIn(Se,S)2 colloidal quantum dots and an Sb-doped TiO2 layer. The device uniquely encodes both polarity and magnitude of light intensity variations into transient photocurrents, preserving critical information without complex circuitry. This enables faster convergence and superior clustering in gesture recognition, and supports a hierarchical HMI system that combines event-driven and frame-based sensing for efficient, low-cost, and robust interaction.
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ZHANG Zinan, SHEN Li, HUANG Fei, RAN Wenhao, WEI Bin, DENG Qingsong, TIAN Jianjun, SHEN Guozhen, WANG Zhuoran (2026). An Event-Driven Sensor Based on Colloidal Quantum Dots for Contactless Human-Machine Interaction. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3997-9
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Frequently Asked Questions
What is the device architecture and how does it achieve event-driven behavior with magnitude encoding?
The device is a two-terminal photodiode with a stack of Sb-doped TiO2, CuIn(Se,S)2 colloidal quantum dots, and PEDOT:PSS. It generates transient photocurrents that encode both the polarity and magnitude of light intensity changes, unlike conventional DVS which only indicates change events. This is achieved through capacitive coupling effects, enabling simple architecture without complex circuits.
How does the event-driven sensor reduce data redundancy compared to frame-based sensors in practical scenarios?
In a simulated 10-second scene at 1920×1080 resolution, the event-based sensor produces an average file size of 7.5 MB, versus 14.8 MB for a frame-based sensor, a 49.3% reduction. This reduction stems from outputting only intensity changes, eliminating redundant static frames, which is critical for low-power, real-time systems.
What is the gesture recognition accuracy and how does it compare to existing systems?
The proposed HMI system achieves a gesture recognition accuracy of over 92.5%. This high accuracy is attributed to the preservation of magnitude information in the event-driven sensor, which enhances feature extraction and clustering performance, leading to faster convergence and superior classification.
What are the scalability and cost implications of the solution-processed fabrication method?
The device is solution-processed, enabling low-cost, large-area fabrication. The two-terminal architecture simplifies integration and reduces material and processing costs compared to complex DVS circuits. This scalability is essential for commercial deployment in consumer electronics and robotics.
How does the hybrid HMI system integrate event-driven and frame-based sensing for multi-stage tasks?
The system uses the event-driven sensor for low-latency gesture control of a UAV (reconnaissance) and a frame-based sensor for high-precision gaze control of a UGV (target engagement). This synergy leverages the strengths of each modality: event-driven for efficiency and low latency, frame-based for accuracy, enabling a robust and versatile HMI platform.
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