Bioinspiration in my Summer Research: How I used Nature's Sensing Systems to Approach X-Ray Radiation Sensor Design

Author’s note:

Hi everyone, 

I’m very excited and proud to share my latest blog post, which draws from the research I conducted this summer at the Columbia Laboratory for Unconventional Electronics (CLUE) and from my paper submitted to the Regeneron Science Talent Search.

This summer, I had the privilege to work at Columbia University, where my supervisor, Dr. Ioannis Kymissis, introduced me to a central challenge in modern cancer treatment: radiation therapy. As a key modality for noninvasive cancer care, radiation therapy is used in more than 50% of all cancer cases. Radiation therapy works by delivering highly concentrated beams of X-rays to a localized tumor site to induce apoptosis and destroy cancerous cells. However, these beams can have adverse effects and sometimes damage healthy surrounding tissue. Therefore, improving the precision and dose calibration of the X-rays to better tailor to the patient's needs is essential.

Paper/project title:"Bioinspired Design of Photoacoustic Sensors for X-ray Radiation Therapy."

For a brief description, my project explored how to enhance X-ray radiation therapy by developing two parallel tracks for a bioinspired photoacoustic sensor model. These sensors detect the pressure waves generated when a material absorbs a pulsed light source, offering a potential pathway toward more accurate, real-time dose monitoring.

This blog post specifically zooms in on the design process behind my sensor device—on brand as always, highlighting how I used bioinspiration and how sensing systems in nature guided my choices in materials selection and device architecture.

Hope you enjoy! 

-Sophie 

The following are selected snippets of a full research paper submitted to Regeneron: 

Bioinspiration: Unconventional Approaches to X-ray Detector Design

Given the drawbacks in current technologies, such as single use, non real-time, radiation damage and inaccuracy, the case for a novel approach to robust electronic detector design is compelling. We looked at unconventional approaches to transducers to overcome current limitations. In my previous research, I worked on bioinspired approaches to materials science, which focuses on synthetic technology designed from structures and properties found in the natural world. The biological tools of nature have evolved over millions of years, are highly adaptive, and present a variety of unique and creative approaches. While the systems might seem unusual, they are often perfectly suited to the task in hand, providing a useful mindset when designing solutions to complex technical problems. The process can help us nurture fragile ideas and innovate beyond the building blocks we are familiar with. It does not mean the choices of materials have to be biological. For this project, I drew inspiration from processes such as mechano-and electroreception and photon energy conversion (check out the figure below!). Many animals have unique sensing systems: in hammerhead sharks, electroreception is used in thousands of ampullae spread across their flattened head to detect weak electric fields, while mechanoreception along their lateral line system allows further detection of movement in the water. The movement of their prey (e.g. a small fish) generates a pressure wave that causes water molecules to move, a form of acoustic energy sensed by the predator through vibrations which are converted to electrical impulses and sent to the brain. Similarly, otters rely on their highly sensitive whiskers and even their paws for sensing acoustic waves in water. Another important principle from bioinspiration is robustness. Robust doesn’t necessarily mean strong in the traditional sense, it can also mean adaptable. During photon absorption in plants, the Light Harvesting Complex II (LHCII, also called photosystem II) can have a physical and mechanical response: Hind et al. used electron microscopy to observe LHCII membrane crystals disassemble when exposed to light and then reassemble in the dark. The key outcome is when excess energy is absorbed, the energy is diverted or dissipated instead of overwhelming the system and destroying the material. When addressing the problem of X-ray detection, I incorporated an understanding of the principles of sensing, transducers and robustness. Bioinspiration serves to illustrate how energy conversion can take many unconventional forms, and how adaptive materials might be able to withstand high-energy X-rays. Clarification of contribution: My research advisor (Professor Ioannis Kymissis) provided the idea of using photoacoustic sensing, and some aspects and principles of X-ray photoacoustic imaging have been described in the literature. Using my previous research experience in bioinspired polymer thin film ferroelectrics, I contributed to ideas in device design, materials selection for sensing, and concepts related to energy transfer. I then performed the experiments and characterization that allowed me to fabricate the devices and test my hypothesis.

Biological and Bioinspired sensing: (a) Electroreception, (b) Optical transduction: plant-light harvesting complex LHC-II induces a protective mechanical response, (c) Capacitive and vibrational sensing in otters, (d) Biomimetic piezoelectric sensing. Select images from the research papers below. Figure compiled by me.

Experimental Design of a Photoacoustic Sensor

The model we arrived at for this project was a photoacoustic sensor: photon absorption, acoustic wave generation, and subsequent transfer of mechanical to electrical energy. The X-ray beam is absorbed by the material, and, like a shockwave, causes minute localized temperature increases. The thermal expansion creates a pressure wave – an acoustic signal in the ultrasonic frequency range that can be detected as mechanical vibrations causing a change in volume (mechanical stress) of the host material. This change in volume, V, can be registered as a generation of an electric charge, provided the host material is piezoelectric. We wanted a material that would absorb X-rays, create an acoustic resonance, and then transfer that energy to the host material (a piezoelectric), able to register an electrical response. Ultimately, the detector would be a matrix array composed of photoacoustic elements that could detect the radiation and use signal processing to generate a 2D or 3D image.

Selected References:

1] Zhao, N.; Wang, Z.; Cai, C.; Shen, H.; Liang, F.; Wang, D.; Wang, C.; Zhu, T.; Guo, J.; Wang, Y.; Liu, X.; Duan, C.; Wang, H.; Mao, Y.; Jia, X.; Dong, H.; Zhang, X.; Xu, J. Bioinspired Materials: From Low to High Dimensional Structure. Advanced Materials 2014, 26 (41), 6994–7017. https://doi.org/10.1002/adma.201401718.

2] Whitesides, G. M. Bioinspiration: Something for Everyone. Interface Focus. Royal Society of London May 15, 2015. https://doi.org/10.1098/rsfs.2015.0031.

3] Naik, R. R.; Singamaneni, S. Introduction: Bioinspired and Biomimetic Materials. Chem. Rev. 2017, 117 (20), 12581–12583. https://doi.org/10.1021/acs.chemrev.7b00552.

4] Guo, Z. H.; Wang, H. L.; Shao, J.; Shao, Y.; Jia, L.; Li, L.; Pu, X.; Wang, Z. L. Bioinspired Soft

Electroreceptors for Artificial Precontact Somatosensation. Sci. Adv. 2022, 8 (21).

https://doi.org/10.1126/sciadv.abo5201.

5] Zhao, Z.; Yang, Q.; Li, R.; Yang, J.; Liu, Q.; Zhu, B.; Weng, C.; Liu, W.; Hu, P.; Ma, L.; Qiao, J.;

Xu, M.; Tian, H. A Comprehensive Review on the Evolution of Bio-Inspired Sensors from Aquatic Creatures. Cell Rep. Phys. Sci. 2024, 5 (7), 102064. https://doi.org/10.1016/j.xcrp.2024.102064.

6] Peleshanko, S.; Julian, M. D.; Ornatska, M.; McConney, M. E.; LeMieux, M. C.; Chen, N.;

Tucker, C.; Yang, Y.; Liu, C.; Humphrey, J. A. C.; Tsukruk, V. V. Hydrogel‐Encapsulated Microfabricated Haircells Mimicking Fish Cupula Neuromast. Advanced Materials 2007, 19 (19), 2903–2909. https://doi.org/10.1002/adma.200701141.

7] Hind, G.; Wall, J. S.; Varkonyi, Z.; Istokovics, A.; Lambrev, P. H.; Garab, G. Membrane Crystals of Plant Light-Harvesting Complex II Disassemble Reversibly in Light. Plant Cell. Physiol. 2014, 55 (7), 1296–1303. https://doi.org/10.1093/pcp/pcu064.