# Unlocking the potential of High-speed widefield Imaging

> **NIH NIH R21** · UNIVERSITY OF CALIFORNIA SANTA BARBARA · 2022 · $211,769

## Abstract

Project Summary:
Widefield imaging and spatial multiplexing are crucial to advancing the field of
neuroscience. Current imagers do not offer the speed and versatility needed for
calcium or voltage imaging experiments. In the case of lifetime imaging the
functionality is completely lacking in CMOS imagers. The problem is more subtle
than it seems because it is not just a matter of brute force speed-up through
technology. Speed increases come with large amounts of power dissipation and
the need for faster data interfaces. One imaging technique with the potential to
solve this issue is the single photon avalanche detector (SPAD). SPADs by virtue
of operation result in digital pulse practically eliminating read noise that
commonly plagues regular imagers. However, SPAD imagers till date have not
seen widespread use due to low pixel density. One of the greatest advantages of
the SPAD imager is its ability to perform time correlated measurements, enabling
lifetime imaging. Lifetime imagers can yield absolute quantitative measurements
not possible with regular imaging modalities. However, the current SPAD
imagers take seconds to minutes to compute a lifetime image, much too slow for
neural imaging. We propose to overcome these fundamental barriers by
innovating at the device, architecture and packaging levels. Our proposed
approach utilizes a transistor amplified SPAD design coupled with in pixel analog
counting and lifetime estimation. These two innovations make it possible to read
the pixel level data at a slower rate, while maintaining a fast frame rate. We
additionally propose a new chip level integration approach which packages the
imager die and processing die in a silicon package enabling reading from
subarrays. This approach enables the imager to maintain the frame rate of the
pixel subarray as the pixel density scales. Finally, we demonstrate the
advantages of our imager by imaging dendritic activity, both in intensity and
lifetime imaging modes, in neural cultures at unprecedented spatiotemporal
scales.

## Key facts

- **NIH application ID:** 10517241
- **Project number:** 1R21EY034291-01
- **Recipient organization:** UNIVERSITY OF CALIFORNIA SANTA BARBARA
- **Principal Investigator:** Luke Satish Kumar Theogarajan
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $211,769
- **Award type:** 1
- **Project period:** 2022-08-01 → 2025-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10517241

## Citation

> US National Institutes of Health, RePORTER application 10517241, Unlocking the potential of High-speed widefield Imaging (1R21EY034291-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10517241. Licensed CC0.

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