Free Open Source Reference Design
At the pinnacle of the COVID-19 crisis in March 2020, many of us watched from home as frontline employees fought to uphold the societal scaffolding. Meanwhile, engineering design firm, Connected Development (CD), took a proactive approach to keeping vulnerable workers safe. Connected Development collaborated with other companies in the TTI, Inc. Family of Specialists, including TTI, Inc., Mouser Electronics, and Symmetry Electronics to develop a contactless wrist temperature scanner (Figure 1) to be used at the TTI, Inc. distribution warehouse in Texas. Then, in a true moment of altruism, CD created an open source design of the temperature scanner for others to utilize for their unique use case.
Figure 1: Connected Development’s Thermal Body Temperature Scanner
Source: Symmetry Electronics
Open Source Contactless Temperature Scanner Benefits
While the wrist temperature scanner* is not available for sale, the open source design is free and includes the full BOM and Github files needed for intermediate-level engineers to develop a scanner of their own. Many temperature scanners on the market are large, expensive, and require additional personnel to operate. Connected Development’s open source temperature scanner is compact, efficient, cost-effective, and completely contactless.
*The wrist temperature scanner design can be modified to be used to scan other parts of the body. The temperature reading range would need to be adjusted accordingly to ensure accurate results.
Body Temperature Scanner Main Components
The free-standing temperature scanner design (Figure 2) is centered around a development board, temperature sensor, LED, and buzzer PCB and provides for reliable temperature readings and proximity detection.
Figure 2: CD's Temperature Scanner Base Design
Source: Connected Development
The following are key features and specifications of the components that make up the temperature scanner design:
Silicon Labs’ EFM32 Tiny Gecko TG11 Starter Kit (Figure 3): Integrating a 32-bit ARM® Cortex-M0+ CPU, the Tiny Gecko TG11 Starter Kit makes development quick and easy. The development board comes equipped with USB connectivity, advanced energy monitoring, SEGGER J-Link on-board debugging, Silicon Labs Si7021 Relative Humidity and Temperature sensor, and more.
Figure 3: Silicon Labs’ Tiny Gecko TG11 Starter Kit Source: Silicon Labs
TE TSD305 Digital Thermopile Sensor: Used to determine body temperature for the scanner, the TE TSD305 features a wide measurement range of 0-100°C, compact design, measurement accuracy of up to ±1°C, I2C Interface, low current consumption, and a wide operating temperature range of -10°C to +85°C.
TDK Piezoelectric Buzzer: Used to alert of temperature results, TDK’s Piezoelectronic Buzzer features a sounding body (unimorph), low power consumption, and serves as a musical tone oscillator and buzzer.
Cree PLCC6 3 in 1 SMD LED: Provides for a visual cue as to whether or not the body temperature is within the ideal range. Cree’s SMD LED is water-resistant (IPX8) and offers a wide viewing angle and high brightness, making it optimal for use for outdoor applications.
The firmware for the automated thermal body temperature scanner was written by Connected Development’s internal software team. Engineers can access the project schematics, BOM, source code, Gerber files, and instructions on Symmetry Electronics’ website.
Contactless Temperature Scanner Common Applications
While the first use case of CD’s body temperature scanner was originally implemented in TTI, Inc.’s warehouse, the following are other applications that are suitable for the design:
Since temperature checks are an imperfect measurement to determine COVID-19 or any other disease or ailment, the manufacturer – TTI, Inc. – disclaims any and all responsibility or liability for any harm to anyone resulting from the use of this system.
About Connected Development
Founded in 2009, Connected Development is a leading wireless, M2M, and IoT engineering firm. Having worked with companies like Ericsson, Motorola, Sony Ericsson, Sierra Wireless, and Nokia–Connected Development specializes in hardware and software design services and can provide support from design reviews to fulfillment of an entire product development cycle. CD’s expertise in regulatory and carrier certification requirements offers customers an advantage in relation to the time and cost-efficiency of an approval process.