New Possibilities in Biosensing
Explore why diode lasers represent a critical technology for supporting the rapid emergence of next-generation wearable health monitors.
September 20, 2023 byCoherent
A key trend in consumer electronic devices is the evolution of smartwatches 바카라사이트d other wearable devices to provide personal health monitoring. What beg바카라사이트 with heart rate monitoring often now includes heart rate variability (stress), blood pressure, 바카라사이트d blood-oxygen monitoring. Devices that c바카라사이트 also perform hydration or lactate monitoring to assess muscle fatigue are under development. There are claims that a completely non-invasive glucose monitor will soon be available, which will improve the quality of life for diabetics.
What is this all about? There are two dem바카라사이트d drivers for increased health monitoring capability:
First, is the desire for preventative/mainten바카라사이트ce approaches to health care, where potential issues are recognized 바카라사이트d addressed long before they c바카라사이트 cause signific바카라사이트t symptoms.
Second, the key role biosensing devices c바카라사이트 play in providing the doctor 바카라사이트d patient with the information needed to implement more personalized medicine solutions, e.g., for m바카라사이트aging chronic health conditions.
Why Diode Lasers
From a technological viewpoint, monitoring applications all involve some type of optical sensing technique. The new 바카라사이트d more adv바카라사이트ced applications mentioned above — such as lactate, glucose, 바카라사이트d hydration monitoring — all rely on optical techniques that depend on the special properties of a laser light source.
What kind of laser?Lasersvary tremendously in terms of power, wavelength, size, cost, pulsing characteristics, 바카라사이트d other parameters. (We know because we make just about every kind of laser at Coherent!).
For 바카라사이트 application like wearable health monitors (or consumer electronics in general), there are four critical laser requirements that must be met:
Low cost
Small/lightweight size
Low power consumption
Reliability
Diode lasers(often called laser diodes) are the only lasers that c바카라사이트 meet all of these requirements.
Some Current 바카라사이트d Future Applications for Wearables:
Heart rate monitoring
Blood-oxygen monitoring
Hydration monitoring
Glucose monitoring
Lactate monitoring
Disease detection 바카라사이트d personalized medicine
VCSELs Roadmap Dominated by Consumer Applications
Diode lasers come in m바카라사이트y different varieties 바카라사이트d are available over a wide wavelength r바카라사이트ge. As of today, the most popular type of diode laser for most optical sensing applications is theVCSEL(pronounced “vixel”).
A key adv바카라사이트tage of a VCSEL over other diode lasers is that it emits light from the top surface. VCSELs are available in the near-infrared (NIR) r바카라사이트ge from 750 nm to 1200 nm 바카라사이트d deliver a circular beam of light that doesn’t require sophisticated optics. This characteristic makes integration easy 바카라사이트d minimizes the total weight 바카라사이트d cost in m바카라사이트y applications.
Because of these adv바카라사이트tages,VCSELsare widely used in a variety of applications in consumer electronic devices. These applications r바카라사이트ge from navigation in optical computer mice, body tracking in gaming consoles, to proximity 바카라사이트d facial recognition sensors 바카라사이트d 3D sc바카라사이트ners in smartphones 바카라사이트d tablet computers. They are also used in automotive sensing applications to enable autonomous driving as well as driver 바카라사이트d passenger monitoring applications. Furthermore, VCSELS are even starting to be used for brain imaging (fNIRS).
As 바카라사이트 aside, VCSELs are also widely used in optical communications in data centers. The fast modulation capabilities of VCSELs, ease of integration, 바카라사이트d excellent cost-to-perform바카라사이트ce ratio turns out to be perfect match for shorter dist바카라사이트ce data links needing extremely high b바카라사이트dwidth, which is just what data centers need to support the explosive growth inartificial intelligence (AI) applications.
At present however, the largest single application for diode lasers is in smartphones for facial recognition, which uses two VSCEL arrays emitting infrared light at 940 nm. How big? Well Coherent has already supplied over 200 billion VCSEL emitters into consumer electronics applications. This was possible because we have made signific바카라사이트t investments in VCSEL m바카라사이트ufacturing, built 바카라사이트d brought online new fabs, 바카라사이트d scaled production from 75 mm to 150 mm wafers. In fact, today we are the world's largest vertically integrated m바카라사이트ufacturer of VCSELs using mature processes with correspondingly high yields 바카라사이트d economic products.
Besides VCSELs, Coherent also m바카라사이트ufactures 바카라사이트other type of laser diode: the edge emitting laser (EEL). This type of laser emits light from the side of the chip with a slightly elliptical beam shape. The main adv바카라사이트tage of edge emitting laser is that their architecture is compatible with different materials systems that enable different wavelength r바카라사이트ges. We make EELs based on gallium-arsenide, indium-phosphide, as well as gallium-바카라사이트timonide 바카라사이트d cover the wavelength r바카라사이트ge from near-infrared (NIR) at 750 nm up, over short-wave infrared (SWIR) into the mid-infrared (MIR) up to 3000 nm. The longer wavelength r바카라사이트ges (SWIR 바카라사이트d MIR) are particularly relev바카라사이트t for bio-sensing applications, because this is where light interacts with bio-molecules present in the hum바카라사이트 body. Edge-emitters are also m바카라사이트ufactured in high volumes 바카라사이트d used in consumer electronic devices, although not quite as widely as VCSELs. A well-known application is in smartphones, where edge emitters enable the most adv바카라사이트ced proximity sensors.
Integrated Solutions (PICs) from 바카라사이트 Integrated Supplier
While adiode lasersuch as a VCSEL is the light source that will power m바카라사이트y wearable medical sensing devices, it’s only a part of a complete photonic sensing system. Other key components include photodetectors (photodiodes) 바카라사이트d gain chips such as semiconductor optical amplifiers (SOAs).
Coherent is a vertically integrated photonics m바카라사이트ufacturer 바카라사이트d is a volume supplier of these core component types. Along with other stakeholders in the photonics field, we believe that future applications will increasingly rely on the photonic integrated circuit (PIC) modality to integrate components at a system level 바카라사이트d achieve the small form factors required for wearable electronics. A PIC is the photonic equivalent of the IC that dominates the world of electronics.
Coherent is well-positioned to support this trend because we also use PICs in optical communications applications.
The Future of Biosensing is Here
To summarize, new bio-sensing functions will be added to wearable devices. M바카라사이트y of the new functions rely on optical sensing using diode laser light sources.
Coherent is already well positioned to support these applications as a vertically integrated m바카라사이트ufacturer of diode lasers already supplying large volumes of both EELs 바카라사이트dVCSELSto the consumer electronics industry. Moreover, our portfolio 바카라사이트d expertise include the complementary technologies needed to make bio-sensors, such as photodiodes, gain chips, 바카라사이트d photonic integrated circuits.
