# US 2017/0281027 A1 · Optical Arrangement For Power-Efficient, Low Noise Photoplethysmographic Sensor Module > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0281027 A1 - Document ID: US20170281027A1 - Status: Published application - Kind: A1 - Application number: 15/091,205 - Filed: 2016-04-05 - Published: 2017-10-05 - Earliest claimed: 2016-04-05 - Assignees: Silicon Laboratories Inc. - Applicants: Silicon Laboratories Inc. - Inventors: Moshe M. Altmejd; Bruce P. Del Signore; Yahui Zhang - Web page: https://patentgrep.com/patent/US20170281027A1 ## CPC - A61B 5/02427: {Details of sensor} - A61B 5/02055: {Simultaneously evaluating both cardiovascular condition and temperature} - A61B 5/02438: {with portable devices, e.g. worn by the patient} - A61B 5/14552: {Details of sensors specially adapted therefor} - A61B 5/681: {Wristwatch-type devices} - A61B 5/7203: {for noise prevention, reduction or removal} - A61B 5/02444: {Details of sensor (A61B5/02427 takes precedence)} - A61B 2560/0209: adapted for power saving - A61B 2562/046: in a matrix array - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract According to one embodiment, a power-efficient, low noise photoplethysmographic (PPG) sensor module is provided herein comprising at least one light emitting diode (LED) and at least one photodetector. The LED is generally configured for emitting light, and is positioned on the PPG sensor module for transmitting the emitted light into biological tissue. The photodetector is generally configured for detecting a portion of the light that is transmitted by the LED into the biological tissue and reflected back to the photodetector. The photodetector is an elongated photodetector having a longer dimension that is at least 1.5 times larger than a shorter dimension of the elongated photodetector. By positioning the elongated photodetector on the PPG sensor module, such that the longer dimension is facing towards the first LED, the elongated photodetector is configured to collect substantially more of the reflected light, thereby increasing the signal-to-noise ratio of the detected signal. ## Claims ### Claim 1 A photoplethysmographic (PPG) sensor module, comprising: a first light emitting diode (LED) configured to emit light, wherein the first LED is positioned on the PPG sensor module to transmit the emitted light into biological tissue; and an elongated photodetector configured to detect a portion of the light that is transmitted by the first LED into the biological tissue and reflected back to the elongated photodetector, wherein a longer dimension of the elongated photodetector is at least 1.5 times larger than a shorter dimension of the elongated photodetector, and wherein the elongated photodetector is positioned on the PPG sensor module, such that the longer dimension is facing towards the first LED. ### Claim 2 (depends on 1) The PPG sensor module as recited in claim 1, wherein the longer dimension of the elongated photodetector is approximately 1.5 to approximately 8 times larger than the shorter dimension of the elongated photodetector. ### Claim 3 (depends on 1) The PPG sensor module as recited in claim 1, wherein the elongated photodetector is further positioned on the PPG sensor module, such that a line passing through a center point of the first LED in a plane of the PPG sensor module substantially bisects the longer dimension of the elongated photodetector. ### Claim 4 (depends on 1) The PPG sensor module as recited in claim 1, further comprising a second LED, which is configured to emit light and positioned on the PPG sensor module to transmit the emitted light into the biological tissue. ### Claim 5 (depends on 4) The PPG sensor module as recited in claim 4, wherein the elongated photodetector is positioned on the PPG sensor module between the first LED and the second LED, such that a line passing through a center point of the first LED and a center point of the second LED in a plane of the PPG sensor module substantially bisects the longer dimension of the elongated photodetector. ### Claim 6 (depends on 4) The PPG sensor module as recited in claim 4, wherein the elongated photodetector is further positioned on the PPG sensor module between the first LED and the second LED, such that a line passing through a center point of the first LED and a center point of the second LED in the plane of the PPG sensor module passes through a top half portion of the longer dimension of the elongated photodetector. ### Claim 7 (depends on 4) The PPG sensor module as recited in claim 4, further comprising a third LED and a fourth LED, each of which are configured to emit light and positioned on the PPG sensor module to transmit the emitted light into the biological tissue. ### Claim 8 (depends on 7) The PPG sensor module as recited in claim 7, wherein the elongated photodetector is further positioned on the PPG sensor module between the third LED and the fourth LED, such that a line passing through a center point of the third LED and a center point of the fourth LED in the plane of the PPG sensor module passes through a bottom half portion of the longer dimension of the elongated photodetector. ### Claim 9 (depends on 1) The PPG sensor module as recited in claim 1, further comprising an additional elongated photodetector, which is configured to detect a portion of the light that is transmitted by the first LED into the biological tissue and reflected back to the additional elongated photodetector: wherein a longer dimension of the additional elongated photodetector is at least 1.5 times larger than a shorter dimension of the additional elongated photodetector; and wherein the additional elongated photodetector is positioned on the PPG sensor module, such that a line passing through a center point of first LED in the plane of the PPG sensor module substantially bisects the longer dimension of the elongated photodetector and the longer dimension of the additional elongated photodetector. ### Claim 10 (depends on 9) The PPG sensor module as recited in claim 9, wherein the first LED is arranged between the elongated photodetector and the additional elongated photodetector, such that a first distance separating the elongated photodetector and the first LED is substantially greater than or substantially less than a second distance separating the first LED and the additional elongated photodetector. ### Claim 11 A photoplethysmographic (PPG) sensor module, comprising: a first light emitting diode (LED) and a second LED, each configured to emit light and positioned on the PPG sensor module to transmit the emitted light into biological tissue; a photodetector configured to detect a portion of the light, which is transmitted by at least one of the first and second LEDs into the biological tissue and reflected back to the photodetector; and wherein the photodetector is arranged on the PPG sensor module between the first and second LEDs, such that a first distance separating the photodetector and the first LED is substantially greater than or substantially less than a second distance separating the photodetector and the second LED. ### Claim 12 (depends on 11) The PPG sensor module as recited in claim 11, wherein the first distance is approximately 2 to approximately 16 times greater than or less than the second distance. ### Claim 13 (depends on 11) The PPG sensor module as recited in claim 11, wherein the photodetector is an elongated photodetector having a longer dimension, which is at least 1.5 times larger than a shorter dimension of the elongated photodetector, and wherein the elongated photodetector is positioned on the PPG sensor module, such that a line passing through respective center points of the first and second LEDs in a plane of the PPG sensor module also passes through a center point of the photodetector. ### Claim 14 (depends on 11) The PPG sensor module as recited in claim 11, further comprising a third LED and a fourth LED, each configured to emit light and positioned on the PPG sensor module to transmit the emitted light into biological tissue, wherein the photodetector is further arranged on the PPG sensor module between the third and fourth LEDs, such that a third distance separating the photodetector and the third LED is substantially greater than or substantially less than a fourth distance separating the photodetector and the fourth LED. ### Claim 15 (depends on 14) The PPG sensor module as recited in claim 14, wherein the first LED and the third LED are arranged on one side of the photodetector and the second LED and the fourth LED are arranged on an opposite side of the photodetector. ### Claim 16 (depends on 15) The PPG sensor module as recited in claim 15, wherein the first distance is substantially equal to the third distance, and wherein the second distance is substantially equal to the fourth distance. ### Claim 17 (depends on 15) The PPG sensor module as recited in claim 15, wherein the first distance, the second distance, the third distance, and the fourth distance are all substantially different from one another. ### Claim 18 (depends on 15) The PPG sensor module as recited in claim 15, wherein the photodetector is an elongated photodetector having a longer dimension, which is at least 1.5 times larger than a shorter dimension of the elongated photodetector. ### Claim 19 (depends on 18) The PPG sensor module as recited in claim 18, wherein the elongated photodetector is further positioned on the PPG sensor module, such that a line passing through a center point of the first LED and a center point of the second LED in the plane of the PPG sensor module passes through a top half portion of the longer dimension of the elongated photodetector. ### Claim 20 (depends on 18) The PPG sensor module as recited in claim 18, wherein the elongated photodetector is further positioned on the PPG sensor module, such that a line passing through a center point of the third LED and a center point of the fourth LED in the plane of the PPG sensor module passes through a bottom half portion of the longer dimension of the elongated photodetector.