Applications of photonic integrated circuits in biomedicine

Introduction

The field of integrated photonics technology, which involves the fabrication of photonic components and circuits on semiconductor chips, has seen tremendous development and innovation in recent years. Originally used primarily in telecommunications and data communications, photonic integrated circuits (PICs) are now finding exciting new uses in biomedicine. This Post explores the various applications of PICs in the biomedical field based on the "International Integrated Photonic Systems Roadmap 2024" (IPSR-I) report [1].

Application fields of PICs in biomedicine

The biomedical applications of integrated photonic technology are very broad and involve many aspects. According to the IPSR-I report, it can be divided into three main areas (Figure 1):

1. Chemical, biological and imaging sensors used directly on patients, patient sample materials or for monitoring patient or population environments

（1） Chemical and biological sensing for diagnostics and health monitoring

The application of integrated circuits in biosensing, especially in diagnosis, was one of the earliest recognized biomedical applications. Application-specific integrated circuits have the advantages of small size, light weight, low power consumption, and can perform multiple tests simultaneously. The global biosensor market size is expected to reach $36.7 billion by 2026, driven in part by the adoption of PIC-based biosensors.
PICs sensors have unique requirements, including the ability to interact with the external environment and sample handling and delivery methods (such as processing blood or saliva samples). If the sensor is spectroscopically based, it must operate over a wider wavelength range than PICs used for telecommunications.
Cost is a key factor as PICs sensors compete with traditional diagnostic methods that can be produced in high volumes at low cost. Disposable PICs diagnostic solutions are not only cost-effective but also meet biosafety requirements for human samples. Implantable photonic devices are also an area of concern but are still in the early stages of development.

（2）Theranostics

Theranostics refers to the concept of using diagnostic methods in conjunction with specific drugs or classes of drugs for specific individuals. Therapeutics, originally developed for cancer treatment, using radiopharmaceuticals for simultaneous treatment and imaging, is now expanding into other areas of personalized medicine by pairing diagnostics with drugs.

（3）Environmental monitoring

Environmental Monitoring Environmental conditions have a significant impact on human health, making chemical and biological sensors for monitoring toxic gases and water pollution an important application area for prior informed consent capabilities. Sensors used in agriculture are also relevant.

（4）Other diagnostic tools

In addition to chemical and biological sensing, ASICs are used in diagnostic tools such as optical coherence tomography (OCT). Optical coherence tomography provides micron-scale three-dimensional imaging of tissue and has been used in a variety of areas, including imaging of the retina, ear tissue, gut, and even neurological imaging.
There are reports of PICs-based OCT methods, such as those based on arrayed waveguide gratings fabricated by Lionix International on a 200 mm wafer scale.

2. Application of integrated photonics in health-related data

（1）Process sensor and diagnostic data

With the widespread use of electronic medical records (EMR) and the increasing amount of personal health data coming from a variety of devices, there is a growing need to store, process and protect sensitive health information. Devices based on PICs are well suited to meet these needs.
Data from biological and chemical sensors based on PICs must be aggregated and monitored over time to reveal changes in an individual's health status. While software packages that analyze continuous wearable device data already have this capability, we can expect this capability to expand rapidly with the emergence of new wearable sensors and integration with central lab or point-of-care testing.

（2）Artificial Intelligence and Machine Learning

An early application of artificial intelligence and machine learning (AI/ML) in biomedicine is likely to be in image analysis, enabling rapid evaluation of results from X-rays, MRI, positron emission computed tomography, and other imaging modalities. These systems require significant data input/output, storage, and computing power to run AI models, making PICs ideally suited for such applications.

3. Digital twins and microphysiological systems (also known as tissue chips) and other emerging fields that will be launched in the future

（1）Digital twin

The concept of digital twin: a computational model used to evaluate the functional status of equipment and predict failures. It has been widely used in manufacturing industry. In the biomedical field, digital twins of humans, also known as "virtual human twins" (VHTs), are also being explored. Currently, VHTs have been used to model aspects such as the human immune system, and it is expected that in the long run, VHTs will enable accurate modeling of individuals.
When combined with real patient data from PICs diagnostics and biosensors, VHTs will be able to more precisely target treatments to individuals.

（2）Microphysiological System (MPS)

A microphysiology system, also known as a tissue chip or "organ-on-a-chip," is a device that uses precision microfluidic technology to three-dimensionally culture multiple cell types to simulate human organs. These devices serve as tools for biological experiments and are attractive alternatives to animal disease models for testing new drugs.
In December 2023, the U.S. Congress passed the FDA Modernization Act 2.0, requiring the FDA to accept MPS data as an optional substitute for animal data when considering new drug applications. MPS development is considered a significant market opportunity, with one early-stage company (Emulate) estimated to have a valuation of $500 million to $1 billion.
While MPS experiments have traditionally relied on post hoc fluorescence microscopy and liquid sampling, sensor development for continuous monitoring has become a recognized need. An example of how this can be achieved using integrated photonic sensors has been published, and we can expect this field and its demand for PICs-based sensors to expand rapidly.

Key considerations and challenges

1. Sample processing and delivery

For PICs sensors that interact directly with patient samples such as blood or saliva, sample handling and transport methods are critical. This includes factors such as sample handling, preparation, and interfacing with PICs sensors.

2. Packaging and integration

Packaging and integration of PICs sensors and devices are critical considerations, especially for implantable or wearable devices. Factors such as biocompatibility, miniaturization and power management must be addressed.

3. Cost and Disposability

Compared with traditional diagnostic methods, PICs sensors have high yield and low cost, so cost control is a major challenge. Single-use PICs diagnostic solutions need to be cost-effective while meeting biosafety requirements for human samples.

4. Data security and privacy

As personal health data continues to grow, ensuring data security and privacy is a serious challenge. Devices and systems based on PICs must take strong measures to protect sensitive personal information.

Conclusion

Biomedical applications of photonic integrated circuits (PICs) are diverse and developing rapidly. From chemical and biological sensing for diagnostics to data processing to emerging areas such as digital twins and microphysiological systems, PICs will revolutionize every aspect of healthcare.
As biomedical technologies based on PICs continue to develop and be applied, it will be crucial to address key issues and challenges such as sample processing, packaging, cost, and data security. To realize the full potential of integrated photonics technologies in biomedicine, collaborative collaboration between researchers, industry players and regulatory agencies is important.

[1] https://photonicsmanufacturing.org/sites/default/files/documents/biomedical_application_guide_-_ipsr-i_2024.pdf

Preprint

Preprint

Applications of photonic integrated circuits in biomedicine