Nexisense Medical Gas Flow Sensor: High-Precision Flow Monitoring Solutions for Hospital Gas Supply Systems and Medical Equipment

Technical Principle and Key Characteristics of Medical Gas Flow Sensors

Medical gas supply systems involve multiple gases with strict purity requirements (such as medical oxygen ≥99.5%, medical air, N₂O, CO₂). Flow control directly affects patient treatment outcomes and safety. The Nexisense series primarily adopts MEMS thermal mass flow (thermal diffusion principle) and differential pressure technologies. The former achieves zero-pressure-loss mass flow detection through micro-heating elements and temperature difference measurement, while the latter is based on Bernoulli's equation with Pitot tube / Venturi tube structures.

Typical Performance Indicators:

• Range: 0.1-300 L/min (oxygen/air calibrated), extendable to 500 L/min

• Accuracy: ±(1.5% RD + 0.5% FS)

• Pressure Drop:<200 Pa (thermal type typically <50 Pa)

• Response Time:<20 ms

• Repeatability: ±0.5% FS

• Working Pressure: 0-1.0 MPa

• Certification: ISO 13485 compatible, GB 50751 compliant, biocompatibility assessment

The sensor includes built-in temperature/pressure compensation algorithms and supports switching of multiple gas calibration coefficients to maintain high linearity and stability across different media.

Main Application Scenarios and Hospital Project Practices

Nexisense flow sensors are widely used in hospital gas supply and medical equipment fields.

Central Medical Gas Pipeline System (MGPS) Monitoring
Deployed downstream of gas manifolds, zone valve boxes, and bedside terminal units to achieve real-time flow metering of oxygen, air, N₂O, and CO₂ in various departments. 4-20 mA/RS485 output connects to gas monitoring host or BMS, supporting total consumption statistics and zone alarms (flow anomaly > set value triggers sound/light/SMS). In a new construction project of a tertiary Class A hospital, >800 flow nodes were integrated, combined with pressure sensors for leak detection and usage traceability, meeting GB 50751 design flow requirements and reducing gas waste by approximately 18%.

Ventilator and ICU Gas Delivery Control
Embedded in ventilator gas circuit modules to monitor inhaled oxygen concentration (FiO₂) and tidal volume-related flow. Digital I²C/UART output supports closed-loop proportional valve regulation for precise oxygen mixing and PEEP control. Actually deployed in multiple ICUs, the sensor maintains <±2% accuracy="" in="" high-humidity="">90% RH) environments, assisting ventilation management for ARDS patients.

Anesthesia Machine and Operating Room Gas Management
Monitors N₂O, O₂, air, CO₂ (pneumoperitoneum) flow, supporting multi-gas ratio control and waste gas recovery monitoring. Project case: In the surgical department of a large general hospital, Nexisense modules were integrated into anesthesia workstations, with flow data linked to AGSS waste gas systems to ensure N₂O emission concentration<25 ppm, meeting occupational exposure limits.

Oxygen Concentrators and Gas Purification Equipment
Used for PSA oxygen concentrator outlet flow monitoring and cycle control to ensure stable oxygen production flow and qualified purity.

Selection Guide and System Integration Considerations

Selection Key Parameters:

• Measurement Principle: Thermal type preferred for low-pressure-drop, high-precision scenarios (e.g., ventilators); differential pressure type suitable for high-flow pipelines.

• Range and Gas Type: Oxygen/air 0-100 L/min, N₂O/CO₂ 0-50 L/min; calibration gas must be specified.

• Output Interface: Analog 4-20 mA/0-5 V, digital I²C/SPI/UART/RS485, convenient for embedded or PLC access.

• Pressure Drop and Pipe Diameter: Channel compatible with 6-12 mm standard medical tubing, pressure drop<100 Pa preferred for ICU equipment.

• Protection and Certification: IP54 or higher, materials compliant with USP Class VI biocompatibility.

Integration Considerations:

• Installation Direction: Gas flow direction consistent with arrow; upstream straight pipe section >10D, downstream >5D to reduce turbulence.

• Gas Path Design: Install pre-filter dryer upstream to prevent condensate and particulate contamination of sensor membrane.

• Electrical Isolation: Use isolated power supply and optocoupler to prevent ground loops and electromagnetic interference (IEC 60601-1-2).

• System Calibration: Factory NIST traceable multi-point calibration; recommend annual or after cumulative flow >10⁶ L on-site verification.

• Integration with Monitoring Platform: Modbus RTU/MQTT protocol access to hospital gas management system, supports BACnet extension.

• Alarm Logic: Set multi-level thresholds (low-flow warning, zero-flow supply interruption alarm), link to valve cutoff or backup gas source switchover.

  
  

OEM Customization and Bulk Supply Advantages

Nexisense provides medical-grade OEM/ODM services, including:

• Custom range, channel geometry, gas calibration coefficients, and multi-gas switching algorithms

• Integration of specific interfaces (M12 connector, medical quick-connect) and pre-installed tubing components

• Supply of bare die/module/finished meter form, supporting customer brand laser engraving

• Biocompatibility coating, EO/gamma sterilization compatibility validation

Bulk supply covers hundreds to tens of thousands of units, delivered according to hospital new construction/expansion cycles, with tiered pricing, stocking agreements, and joint EMC/reliability testing.

Frequently Asked Questions (FAQ)

1. How stable is the Nexisense thermal flow sensor in high-humidity medical oxygen environments?
      Built-in heating compensation and hydrophobic coating, annual drift

   <±1.5%, typical="" lifespan="">8 years.

2. How to achieve aggregation and zone management of multi-terminal flow data in central gas supply systems?
      Via RS485 bus or wireless LoRa networking, gateway collects data and maps it to BMS via Modbus for zone accumulation and real-time trend analysis.

3. How does the sensor handle cross-interference in anesthesia machine N₂O measurement?
      Thermal mass flow based on thermal property differences; N₂O dedicated calibration coefficient cross-interference<3%, combined with pressure compensation to ensure accuracy.

4. How to meet GB 50751 redundancy requirements for flow monitoring during system integration?
      Critical areas use dual-sensor parallel configuration (primary + backup) with automatic switchover and fault self-diagnosis output.

5. What is the impact of embedded module response time on ventilator control?
   <15 ms response supports fast pressure/flow closed-loop, reducing trigger delay and patient-ventilator asynchrony.

6. What is the minimum order quantity for OEM customized multi-gas calibration modules?
      Standard oxygen/air modules start at 1000 units; multi-gas switching projects start at 3000 units; development cycle 8-12 weeks.

7. How applicable is the sensor in negative pressure vacuum systems?
      Negative pressure resistant design (-90 kPa and below), suitable for vacuum suction terminal flow monitoring with accuracy maintained at ±2%.

8. How to interface gas consumption data with hospital HIS/BMS systems?
      Supports MQTT/HTTP protocol, cloud API uploads cumulative flow and alarm events, compatible with HL7 standard extensions.

9. Does bulk supply provide per-batch calibration reports and consistency data?
      Yes, provides multi-point calibration certificates, batch statistical analysis, and third-party metrology verification support.

10. For new tertiary hospital projects, what is the recommended flow monitoring point density and threshold strategy?
       1 point per bedside in ICU/operating rooms, 2-4 points per zone valve box; set low-flow warning at<80% of set value, supply interruption alarm at <50%, linked to backup gas source.

Conclusion

Nexisense focuses on providing reliable medical gas flow sensing solutions for hospital engineering companies, medical equipment manufacturers, and gas system integrators. If your company requires sensor selection, integration solutions, or customization support in hospital central gas supply system new construction/renovation, ventilator/anesthesia machine OEM development, or smart hospital gas monitoring platform projects, welcome to contact us for in-depth discussion of specific requirements and cooperation paths. Together, we enhance the safety and precision of medical gas supply to safeguard clinical treatment quality.