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Non-invasive blood glucose detection technology aims to replace traditional invasive blood sampling by using physical methods such as optical, electromagnetic, or thermal means to achieve continuous or intermittent monitoring of human blood glucose concentration. Its core technical challenge lies in extracting characteristic parameters highly correlated with blood glucose concentration from extremely weak physiological signals and ensuring that the measurement process is not interfered with by internal or external electromagnetic environments. In such highly sensitive bioelectronic systems, Electromagnetic Compatibility (EMC) has evolved from a compliance requirement into a core architectural element that determines the system's signal-to-noise ratio (SNR), measurement accuracy, and reliability. Leveraging its long-term expertise in precision electronics and EMC, Yintech (YINT) has achieved a key breakthrough in EMC design paradigms specifically for non-invasive blood glucose detection scenarios.
Traditional EMC design for medical electronic devices often relies on passive suppression methods such as shielding, filtering, and grounding. Yintech's innovation lies in proposing an "Active Collaborative EMC Architecture." This architecture treats the detection sensor, signal conditioning circuit, digital processing unit, and wireless communication module as an integrated electromagnetic system for collaborative design. The core principles are: 1) Integrating miniaturized common-mode chokes (CMC) and π-type filters at the sensor front-end to preemptively suppress interference outside the operating frequency band (e.g., specific near-infrared spectrum or RF band), with typical insertion loss exceeding -40dB outside the target band; 2) Employing differential sensing and transmission path design, combined with the high common-mode rejection ratio (CMRR > 100dB) of instrumentation amplifiers (e.g., INA333 grade), to effectively suppress environmental common-mode noise; 3) Deploying a combination of low-noise low-dropout regulators (LDO) and ferrite beads (FB) for critical analog power rails (e.g., ±2.5V), suppressing power supply noise below 10µVrms.
Non-invasive blood glucose detection often employs multi-wavelength spectroscopic analysis or impedance spectroscopy. Yintech designs constant-current drive circuits for the optical emission module, with output current ripple less than 0.1%, combined with metal shields and conductive glass windows to ensure the stability of LED/laser diode (LD) emission while preventing high-frequency switching noise (e.g., from DC-DC converters) from coupling into the optical path. The preamplifier transimpedance amplifier (TIA) circuit for the photodetector (e.g., APD or PIN photodiode) is encapsulated in an independent shielded cavity, with an input-referred noise current density below 5pA/√Hz. The connection between the sensor and the mainboard uses a flexible printed circuit board (FPC) with a shielding layer, which achieves a low-impedance connection (contact resistance < 10mΩ) to the mainboard ground plane via a 360-degree peripheral contact method.
The analog signal chain adopts a staged gain and filtering strategy. Anti-aliasing filtering is performed immediately after the first stage of amplification, with the filter cutoff frequency precisely set based on the sampling rate (typically in the kHz range), and stopband attenuation greater than 80dB. The analog-to-digital converter (ADC) uses a 24-bit Σ-Δ type, whose internal digital filter is programmable to further suppress power-line frequency and harmonic interference in specific bands. An isolated digital interface (e.g., optocoupler or capacitive isolation) is used between the digital processing unit (typically an ARM Cortex-M series MCU) and the ADC to block digital ground noise from flowing back to the analog ground. PCB layout strictly follows zoning principles, with clear separation of analog, digital, and RF areas, connected via single-point grounding or ferrite beads.
To enable data upload, the device integrates Bluetooth Low Energy (BLE) or Wi-Fi modules. Yintech employs a "Time Division Multiplexing and Spectrum Avoidance" strategy: during critical blood glucose signal acquisition periods (typically several seconds), the wireless transmission function is temporarily disabled via software commands; during transmission periods, the channel with the least interference is dynamically selected. The Power Management Unit (PMU) uses multiple independent LDOs to power different subsystems, avoiding crosstalk through power paths. The switching frequency of switching power supplies (e.g., Buck circuits for battery charging) is strictly controlled at specific points and kept away from the sensing signal band, with their switching nodes covered by large-area copper foil and grounded via filter capacitors.
In accordance with IEC 60601-1-2 (Electromagnetic Compatibility Requirements for Medical Electrical Equipment) and YY 0505-2012 (Chinese Medical Industry Standard), Yintech's non-invasive blood glucose monitor prototype has completed a full set of EMC tests. Test data shows: during the radio-frequency electromagnetic field immunity test (80MHz to 2.7GHz, field strength 10V/m), the device's blood glucose reading deviation was less than ±0.1 mmol/L, meeting the requirements of Performance Criterion A; Conducted Emission (CE) and Radiated Emission (RE) test results were both more than 10dB below the CISPR 11 Class B limits, indicating extremely low electromagnetic leakage from the device itself. Furthermore, in simulated tests of complex multi-device coexistence environments (e.g., with mobile phones and Wi-Fi routers present simultaneously), the system maintained a measurement success rate of over 99.5%.
Through system-level active collaborative EMC architecture design, Yintech has improved the signal-to-noise ratio of the non-invasive blood glucose monitor by approximately 15dB, laying a hardware foundation for reliably extracting weak physiologically relevant signals from strong electromagnetic background noise. This technological breakthrough not only enhances the accuracy of single measurements but also provides a key guarantee for achieving long-term, continuous, and stable dynamic glucose monitoring (CGM). In the future, with the further evolution of sensor technology and algorithms, EMC design will be more deeply integrated with technologies such as AI-driven adaptive filtering and real-time interference spectrum sensing, driving non-invasive blood glucose monitoring technology towards higher accuracy and greater robustness. For more technical details and product updates, please refer to the technical documents and whitepapers published on Yintech's official website (www.yint.com.cn).
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