High performance, low cost array for Gesture-Sensing announced by ActLight
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ActLight presents at Photonic Spectra
Serguei Okhonin - ActLight’s Co-founder and CEO, presented the fundamentals and innovation of the Dynamic PhotoDiode, the bre ...
ActLight CEO interviewed by Verve
https://www.verve.vc/blog/interview-serguei-okhonin-actlight/
Actlight on The Business Time
https://thebusinesstime.co.uk/continuous-in-ear-vital-sign-monitoring-challenges/
Technology
High sensitivity
The DPD sensitivity is tuneable down to a single photon.
Low voltage
Our sensor does not require any high voltage. The sensor front-end just uses Vdd.
Low cost
The DPD sensor is fabricated with low costs technologies such as standard CMOS and others.
Digital output
The DPD has high output signal, therefore it can be directly connected to digital circuits.
ActLight’s Dynamic PhotoDiode technology offers technological breakthrough in light sensing and superior Signal-to-Noise ratio (SNR).
Traditionally, photodiodes operate at constant reverse bias voltage giving photocurrent as output. Typically, this photocurrent is weak and requires further amplification. An amplifier introduces additional noise, which becomes crucial at low light conditions. Instead of using DC bias, the DPD operates at pulsed voltages: the applied voltage is switched from reverse to forward bias. This forward bias induces a large forward current after a time delay, so called triggering time, which depends on the light intensity. This way, we measure the delay time of the large forward current instead of the small photocurrent magnitude.
Due to the large output signal, the DPD does not require any amplifier, and it can be directly connected to digital circuits. Absence of the amplifier and its associated noise provides a great improvement in the device performance.
The DPD IP portfolio includes two main versions: Embedded and Stand-Alone.
The Embedded DPD is fabricated with standard CMOS technology and its simple Front-End circuits are integrated on the same chip. The absence of complex analog circuits allows to reduce silicon area and provides a cost-effective integrated solution.
The Stand-Alone DPD benefits from a unique and patented device structure requiring a very simple, low cost manufacturing process and it offers flexibility in terms of device size, making the Stand-Alone Dynamic Photodiode the ideal light sensor solution for markets looking for a high-performance discrete photodiode.
Applications
Biometric sensors for wearable devices
Increased battery life
Due to better signal to noise performance of the DPD sensor, less light is needed to get a PPG sample. A reduction of about 7 times in LED transmitted energy was measured compared to a state of the art system.
Precision
The absence of an analog amplifier improves the signal-to-noise ratio of the DPD, which translates in higher output signal accuracy.
Reduced Cost
Smaller silicon area leads to significant cost reduction. Additionally, our DPD sensor and its read-out front-end circuit are implemented on the same substrate in standard 180 nm CMOS technology.
The light emitted by LEDs and reflected from the wrist is measured with a photodiode. The reflected signal depends on the blood concentration. With each cardiac cycle the heart pumps blood which change reflection and output signal of the photodiode. The modulation of the photodiode signal gives information about vital signs such as heart rate, oxygen saturation (SpO2), and blood pressure.
Biometric sensors using conventional photodiode require signal amplification, and amplifier becomes the main source of noise. ActLight’s Dynamic Photodiode technology provides direct digital output which eliminates the need of the analog amplifier improving system signal to noise ratio. This means that less light is required to obtain the same heart rate signal. ActLight heart-rate monitor requires significantly less light with respect to the state of the art system to get the same output signal quality, significantly reducing the power consumption.
3D ToF camera for mobile applications
High performance at low voltage
The DPD sensor deliver high optical performance and does not require high voltage.
Small pixel size
The DPD sensor array can have a pixel size below 5 um.
Reduced cost
The DPD sensor and its front-end circuit are implemented on the same substrate in standard low cost CMOS technology.
The interest for 3D and range imaging is exponentially increasing due to its exploitation in mobile applications. The most advanced 3D imaging technique is a Time-of-Flight (ToF) method. In this method a depth image is obtained by measuring light propagation time.
The DPD sensor delivers high optical performance which is especially important in the mobile applications where emitted light power is limited. Our dedicated ToF method offers advantages in terms of compact system realization, good performance, and low required computational power.
In current 3D camera sensors, pixel scaling is limited due to complex analog circuits. The DPD's simple digital front-end allows to decrease pixel size below 5 um. Moreover, the Embedded DPD and its read-out front-end circuit are implemented on the same substrate in standard low-cost CMOS technology, and does not require high voltage for its operation.
LIDAR
High performance at low voltage
The DPD sensor delivers high optical performance and does not require high voltage compared to APDs.
High background light immunity
Sensors based on SPADs fail to operate at high background light. ActLight's DPD sensor has high background light immunity.
Reduced cost
Smaller silicon area leads to significant cost reduction. Additionally, our DPD sensor and its read-out front-end circuit are implemented on the same substrate in standard 180 nm CMOS technology.
LIDAR (Light Detection and Ranging) uses a laser light to obtain a depth image. In most of the LIDAR sensors used for mapping and self-driving vehicles the time between the emission and reception of the light is computed to determine the time of flight (ToF). Knowing the speed of light and delay time for the return wave we can compute the distance to the object that caused the light to bounce back. That value is the range information that is reported by the sensor.
LIDAR systems are designed to detect objects at long distances, so typically the reflected light is extremely weak. Thus, the high performance photodetectors are used in LIDARs. Moreover, the weak reflected light should be often detected on top of a strong background light, which makes the measurement even more challenging. The DPD solution is imminently suitable for solid state LIDAR applications since it combines high performance sensing with immunity to the strong background light.
About us
ActLight SA is the start-up company, founded in 2011 and based in Lausanne - Switzerland, whom developed a disruptive technology in the field of light sensors. The 100% owned, patented photonics technology allows to substantially improve the efficiency and accuracy of various light sensing applications in the Internet of Things (IoT) space, like Time-Of-Flight (TOF) based distance measuring (i.e. user detection, gesture control and visual recognition), vital signs monitoring, 3D/2D cameras and much more. ActLight operates in markets like mobile and wearable devices, healthcare/medtech, autonomous driving, drones and robotics.
Our company, powered by its highly innovative R&D spirit and profiting from collaborations with leading institutions such as the internationally renowned EPFL, has swiftly evolved to become a technology leader in its segment. ActLight SA is a fab-less company which operates primarily in a licensing business model where revenues are generated from IP licenses and royalty fees but also from non-recurring engineering (NRE) projects.
ActLight's team consists of experts in the fields of devices, materials, integration process, characterization techniques, circuits design, marketing and business development.
IP protection and sales are performed by top experts located in US, Japan, and Switzerland. Strong advisory board includes both industrial and scientific experts.
Contact
Want to know more?
Contact us at info@act-light.com
ActLight SA
EPFL Innovation Park, Building I, 1015 Lausanne, Switzerland
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