publications

2023

1. 

   Flow Cytometry With Event-Based Vision and Spiking Neuromorphic Hardware

   Steven Abreu, Muhammed Gouda, Alessio Lugnan, and Peter Bienstman

   In Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR) Workshops 2023

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   Imaging flow cytometry systems play a critical role in the identification and characterization of large populations of cells or micro-particles. Such systems typically leverage deep artificial neural networks to classify samples. Here we show that an event-based camera and neuromorphic processor can be used in a flow cytometry setup to solve a binary particle classification task with less memory usage, and promising improvements in latency and energy scaling. To reduce the complexity of the spiking neural network, we combine the event-based camera with a free-space optical setup which acts as a non-linear high-dimensional feature map that is computed at the speed of light before the event-based camera receives the signal. We demonstrate, for the first time, a spiking neural network running on neuromorphic hardware for a fully event-based flow cytometry pipeline with 98.45 testing accuracy. Our best artificial neural network on frames of the same data reaches only 97.51, establishing a neuromorphic advantage also in classification accuracy. We further show that our system will scale favorably to more complex classification tasks. We pave the way for real-time classification with throughput of up to 1,000 samples per second and open up new possibilities for online and on-chip learning in flow cytometry applications.

   @inproceedings{AbreuEtAl2023,
     author = {Abreu, Steven and Gouda, Muhammed and Lugnan, Alessio and Bienstman, Peter},
     title = {Flow Cytometry With Event-Based Vision and Spiking Neuromorphic Hardware},
     year = {2023},
     booktitle = {Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR) Workshops},
     pages = {4138-4146},
   }

2022

1. 

   Hands-on reservoir computing: a tutorial for practical implementation

   Matteo Cucchi,  Steven Abreu, Giuseppe Ciccone, Daniel Brunner, and Hans Kleemann

   Neuromorphic Computing and Engineering 2022

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   This manuscript serves a specific purpose: to give readers from fields such as material science, chemistry, or electronics an overview of implementing a reservoir computing (RC) experiment with her/his material system. Introductory literature on the topic is rare and the vast majority of reviews puts forth the basics of RC taking for granted concepts that may be nontrivial to someone unfamiliar with the machine learning field. This is unfortunate considering the large pool of material systems that show nonlinear behavior and short-term memory that may be harnessed to design novel computational paradigms. RC offers a framework for computing with material systems that circumvents typical problems that arise when implementing traditional, fully fledged feedforward neural networks on hardware, such as minimal device-to-device variability and control over each unit/neuron and connection. Instead, one can use a random, untrained reservoir where only the output layer is optimized, for example, with linear regression. In the following, we will highlight the potential of RC for hardware-based neural networks, the advantages over more traditional approaches, and the obstacles to overcome for their implementation. Preparing a high-dimensional nonlinear system as a well-performing reservoir for a specific task is not as easy as it seems at first sight. We hope this tutorial will lower the barrier for scientists attempting to exploit their nonlinear systems for computational tasks typically carried out in the fields of machine learning and artificial intelligence. A simulation tool to accompany this paper is available online.

   @article{CucchiEtAl2022handson,
     title = {Hands-on reservoir computing: a tutorial for practical implementation},
     author = {Cucchi, Matteo and Abreu, Steven and Ciccone, Giuseppe and Brunner, Daniel and Kleemann, Hans},
     year = {2022},
     journal = {Neuromorphic Computing and Engineering},
     note = {Accepted manuscript},
   }

2019

1. 

   Automated architecture design for deep neural networks

   Steven Abreu

   ArXiv Aug 2019

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   Machine learning has made tremendous progress in recent years and received large amounts of public attention. Though we are still far from designing a full artificially intelligent agent, machine learning has brought us many applications in which computers solve human learning tasks remarkably well. Much of this progress comes from a recent trend within machine learning, called deep learning. Deep learning models are responsible for many state-of-the-art applications of machine learning. Despite their success, deep learning models are hard to train, very difficult to understand, and often times so complex that training is only possible on very large GPU clusters. Lots of work has been done on enabling neural networks to learn efficiently. However, the design and architecture of such neural networks is often done manually through trial and error and expert knowledge. This thesis inspects different approaches, existing and novel, to automate the design of deep feedforward neural networks in an attempt to create less complex models with good performance that take away the burden of deciding on an architecture and make it more efficient to design and train such deep networks.

   @article{Abreu2019automated,
     author = {Abreu, Steven},
     title = {Automated architecture design for deep neural networks},
     year = {2019},
     month = aug,
     journal = {ArXiv},
     issue = {1908.10714},
     archiveprefix = {arXiv},
     eprint = {1908.10714},
   }