## 4 Results  
### Communication Speed Evaluation  
The most important features of s-Guard include stable sensors, wireless communication, and seamless monitoring. Necessarily, this can be assessed mainly by two categories: communication speed and communication errors. This section presents the Bluetooth communication speed function evaluation results. The results will be followed by communication error rate performances that represent the stability of the fast communication in the next Section 4.2. The communication experiment was conducted using the experimental model shown in Figure 7. s-Guard was connected to our custom-developed MAD cleaner communication gateway (Clium) via Bluetooth. This gateway acts as a communication hub for server/personal computer (PC) connections and can also be used as a sanitized intraoral device storage. \begin{table}
\begin{tabular}{c c} \hline \hline
**Classification** & **Specifics** \\ \hline MCU & 64 MHz 32-bit ARM Cortex-M4 \\ Communication Module & Bluetooth 5/ANT/2.4 GHz proprietary \\ Power supply & 1.7 to 3.6 V LDO or DC/DC \\ Memory & 192 KB Flash + 24 KB RAM \\ On-air data rate & 2 Mbps/1 Mbps \\ TX power & Programmable from +4 to –20 dBm in 4 dB \\ \begin{tabular}{c} Sensitivity \\ Radio current consumption DC/DC at 3 V \\ \end{tabular} & \begin{tabular}{c} Bluetooth 5: 93 dBm at 2 Mbps \\ 7.0 mA at +4 dBm TX power \\ \end{tabular} \\ System current consumption DC/DC at 3 V & 0.3 \(\mu\)A in System OFF, no RAM retention, 0.5 \\ \begin{tabular}{c} Hardware security \\ Digital interfaces \\ \end{tabular} & \begin{tabular}{c} 128-bit AES CCM, ECB, AAR \\ SPI master/slave, TWI master/slave, UART, PWM, QDEC, PDM \\ \end{tabular} \\ \
\begin{tabular}{c} Analog interfaces \\ Peripherals \\ Package options \\ \end{tabular} &
\begin{tabular}{c} 12-bit 200 ksps ADC, RNG, GP comparator \\ \(3\times 32\)-bit Timer \\ 6 \(\times\) 6 QFN48 [24] with 32 GPIOs, \(5\times 5\) QFN32 [25] with 16 GPIOs \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Core specifications of MCU, communication module, power supply, etc. \begin{table}
\begin{tabular}{c c} \hline \hline
**Classification** & **Specifics** \\ \hline Temperature Sensor &
\begin{tabular}{c} MAX30101 [26], \(-\)40 Celsius to +85 Celsius \\ operating temperature range \\ LSM6 DSOX [27], iNEMO inertial module: \\ six-axis Sensor & always-on three dimension (3D) accelerometer \\ and 3D gyroscope \\ 64 MHz from 32 MHz external crystal or \\ SpO\({}_{2}\) Oscillators & internal, 32 kHz from crystal [28], RC or \\ synthesized \\ \end{tabular}
\end{table} 
Table 2: Specifications of temperature, six-axis, and SpO\({}_{2}\) sensors. The MAD cleaner communication gateway was then connected to the test PC via a serial connection. Bluetooth communication speed performance was shown in a basic disk operating system (DOS) interface, which was shown in the console command in bits per second (bps). The specifications of the mad cleaner communication gateway and test PC are listed in Table 3.  
The transmission speed results obtained from volunteer test patients are shown in Figure 8. The test environment was conducted according to the specifications mentioned in Section 3.2. All test procedures were approved by the Institutional Review Board (IRB) of Yonsei Severance Hospital (IRB approval number 2-2019-0060). Starting from a set time (time stamp = 0), the transmission speed was measured 26 times (n = 26) with a time interval of 2 s. All results were rounded up to the second decimal place. The results showed an average transmission speed of 91,870.19 bytes per second (standard deviation 136.3), with a population size of 25. The minimum value was 91,745, and the maximum value was 92,010, with a median of 91,869. The first quartile was 91,779.5, and the third quartile was 91,901, with the interquartile range of 121.5. Figure 8: Transmission speed testing box and whisker plot results. Figure 7: Experiment model of s-Guard Bluetooth communication performance.