Pulse-oximeter using MAX30102, AAA battery-powered

パルスオキシメーター MAX30102 使用，単４電池駆動

Of course, it's home brewed. もちろん自作です。

Display 表示

Obviously, I'm alive. 明らかに生きてます。

Schematic 回路図

Nothing special. 普通です。

PCB 基板

Gerber files are here. ガーバーファイルはここです。

BOM 部品表

Item	Description	Brand	QTY
Sensor	MAX30102 breakout	Maxim Integrated, etc	1
MCU	PIC16F1825-I/P	Microchip	1
Display	OLED with SSD1306 or AQM1248A	Sunhokey, etc Akizuki	1
3V3 boost conv	HT7733A (TO-92) or TPS613221ADBV, etc	Holtek TI	1
Schottkey D	SD103A	PANJIT or Vishay	2
Piezo speaker	PKM13EPYH4000-A0	muRata	1
L	100 uH	-	1
C	47 uF electrolytic	-	1
C	22 uF electrolytic	-	1
C	0.1 uF ceramic	-	1
R	1k ohm	-	1
SW	3p toggle or alternate push	-	1
Battery box	AAA x 2	-	1
Pin header	6 pin (ICSP)	-	1
Pin header & jumper	2 pin	-	1 each
Pin socket	7 pin (LCD) or 4 pin (OLED)	-	1
Pin socket	4 pin (MAX30102 board)	-	1-2
PCB	custom	-	1
Nuts & bolts	M3 x 10 mm	-	4 sets
Nuts & bolts	M2.6 x 6 mm	-	1-2 sets
Spacer	3 mm x 3 mm height, resin	-	4
Enclosure	85.5 x 59 x 24 mm, ABS	Akizuki	1

It's less than 25 US$ in total. MAX30102 breakout board with a 1.8V regulator is available from Maxim (MAXREFDES117#) and also from 3rd parties. MAX30101 board can also be used. There are two display options: OLED with SSD1306 and LCD AQM1248A with ST7565R. Choose one of them using #define directive. HEX binary for each display is available. HT7733A is a DC/DC boost converter, which can be substituted with TPS613221ADBV, TPS61097A-33DBV, MAX1724EZK33, or XC9142B33CMR-G. Surface mount pads for these devices are prepared, but not tested. If you use a substitute converter, L/C arrangements and their constants should also be reexamined accroding to datasheet recommendations. You may need a 6-pin male-to-female DuPont wire to connect this PCB to a PIC programmer.

全部で2500円いきません。MAX30102ボードはMaximのMAXREFDES117#などいくつかの種類が入手可能です。MAX30101のでも使えます。ディスプレイは、秋月グラフィックLCDか、SSD1306のOLEDを選べます。ソースコードの#define文で設定してください。HEXファイルはどちらも用意しています。おもて面のパッドはTPS613221ADBVなどHT7733Aの代替品用で、SOTパッケージのHT7733Aには使えません。センサはアマゾンで、それ以外は秋月で手に入ります。基板をPICプログラマーにつなぐには、6pオスメスケーブル（共立電子QIケーブル6S-6Pなど）も必要です。

SpO₂ calculation 計算式

Four options are implemented. Default is option 1.
4つあります。既定では1です。

1. SpO₂ = -33.437 R + 114.9 (linear approximation of Reynolds et al. (1991) Br J Anaesth 67, 638)
   
2. SpO₂ = -17 R + 104 (User guides & manuals 6409, Maxim Integrated)
   
3. SpO₂ = 1.5958422 R² -34.6596622 R + 112.6898759 (Application note 6845, Maxim Integrated)
   
4. SpO₂ = -45.060 R² + 30.354 R + 94.845 (MAX3010x sensor library, SparkFun)
   where R = (AC_red / DC_red) / (AC_IR / DC_IR).
   
   Excel file
   

References 参考

Reynolds et al. (1991) Br J Anaesth 67, 638-643. DOI
Recommended Configurations and Operating Profiles for MAX30101/MAX30102 EV Kits, User guides & manuals 6409, Maxim Integrated
Guidelines for SpO2 Measurement Using the MaximR MAX32664 Sensor Hub, Application note 6845, Maxim Integrated
MAX3010x sensor library, SparkFun. GitHub

DISCLAIMER お断り

This repository is provided "AS IS", without warranty of any kind, either express or implied. Use it on your own responsibility.
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