Acoustic suspension low-temperature transmission system for cell samples

Abstract

The invention discloses a cell sample low-temperature transmission system based on a sound wave suspension principle, and aims to solve the problems of cell damage, low efficiency, poor compatibility with an existing biological sample library and the like caused by a traditional mechanical transmission mode. According to the system, a standing wave sound field is generated in a transmission channel through a high-frequency piezoelectric transducer array (20-40kHz, and the sound pressure level is greater than or equal to 130dB), so that non-contact suspension of a cell sample is realized; a gaseous nitrogen low-temperature environment (-150 DEG C to-196 DEG C) and a helium doping technology (1-2% by volume) are combined, so that the cooling rate (gt; 1000 DEG C / min), inhibiting the formation of ice crystals (volume ratio lt; 0.1%). A phase array cooperative control and AI trajectory prediction algorithm (CNN-LSTM fusion model) is adopted to drive a sample to be transmitted at a high speed of 50mm / s, and the speed is increased by 5 times compared with that of a traditional method. The modular design is compatible with an SBS standard interface (such as a 96-well plate) and an open communication protocol (RS-485 / CAN bus), and supports seamless docking of mainstream biological sample library equipment. Experiments show that the survival rate of cells transmitted by the system is larger than or equal to 99.1%, the ice crystal damage rate is smaller than or equal to 0.3%, the system has full-process automation and data traceability, and an innovative solution is provided for high-throughput and high-activity transmission of biological samples.

Description

Technical Field

[0001] The present invention relates to the field of biological sample processing technology, and specifically to a low-temperature transmission system based on the principle of acoustic levitation, which is used to achieve non-contact high-speed transmission of cell samples and is compatible with the modular design of existing biological sample libraries. Background of the Invention

[0002] 1. Problems with existing technologies:

[0003] Traditional cell sample transmission relies on mechanical grippers or pipe contact transmission, which can easily cause sample damage due to friction, pressure or temperature fluctuations.

[0004] The transmission speed is limited, and conventional systems need to take into account mechanical stability and low-temperature environments, resulting in low efficiency.

[0005] Existing biobank equipment is not standardized enough, and new systems are difficult to be compatible with old facilities, resulting in high upgrade costs.

[0006] 2. Technical pain points:

[0007] Cell activity is sensitive to mechanical contact, and existing technologies cannot balance transmission speed and sample survival rate.

[0008] The transmission stability in low-temperature environments (such as -196°C liquid nitrogen gas phase) is poor, which can easily cause sample freezing or ice crystal damage. Summary of the Invention

[0009] The basic principle of this patent is based on the combination of acoustic levitation technology and low-temperature environment control technology. Through the synergistic effect of non-contact acoustic field force and low-temperature inert gas medium, efficient and lossless transmission of cell samples is achieved. The following is a step-by-step analysis: 1. Acoustic levitation principle: non-contact sample manipulation

[0010] Standing wave sound field generation:

[0011] High-frequency sound waves (20-40kHz) are emitted through a piezoelectric transducer array (e.g., piezoelectric ceramics). These waves form a standing wave field with the reflector within the transmission channel. The nodes (the lowest sound pressure points) and antinodes (the highest sound pressure points) of the standing wave form periodically distributed potential wells, generating an acoustic radiation force perpendicular to the propagation direction.

[0012] Sample suspension mechanism:

[0013] Cell samples (such as frozen cell droplets) are captured and suspended at the node position of the sound field (usually located in the center of the channel) under the action of acoustic radiation force, thereby avoiding physical contact with the container wall or mechanical parts and eliminating damage caused by friction or extrusion. 2. Principle of maintaining low temperature environment: preventing ice crystal damage

[0014] Inert gas cryogenic medium:

[0015] Gaseous nitrogen (temperature range: -150°C to -196°C) generated by evaporating liquid nitrogen is introduced into the transmission channel, replacing the traditional liquid nitrogen immersion method. The gaseous medium not only maintains the low temperature environment but also reduces the disturbance of the sample caused by boiling or turbulence of the liquid medium.

[0016] Ice crystal suppression design:

[0017] By controlling the gas flow rate and temperature gradient (such as PID algorithm adjustment), the sample is always kept in a "vitrified" state (rapid cooling) to avoid the formation of destructive ice crystals inside the cells.

[0018] 3. High-speed transmission principle: Acoustic field phase coordinated acceleration

[0019] Phased Array Control:

[0020] Multiple piezoelectric transducers form an acoustic phase array. By adjusting the acoustic emission timing and phase difference of each transducer, the node position of the standing wave field is dynamically changed. The sample "jumps" forward as the node moves (similar to the particle manipulation principle of optical tweezers). AI trajectory prediction:

[0021] Machine learning algorithms (such as convolutional neural networks) are introduced to analyze sample motion trajectories and environmental parameters (such as airflow disturbances) in real time, dynamically optimize sound field parameters, and ensure stability under high-speed transmission (50mm / s).

[0022] 4. Modular compatibility principle: plug and play design

[0023] Standardized interface adaptation:

[0024] The mechanical interface of the transmission channel adopts the SBS (Society for Biomolecular Screening) standard (such as the 96-well plate size) and docks with the existing biological sample library through magnetic attraction or snap-on structure, without the need to modify the original equipment.

[0025] Open communication protocol:

[0026] The control system supports RS-485 or CAN bus protocols and can directly read the temperature control and inventory data of the sample library to achieve seamless integration.

[0027] 5. System collaborative workflow

[0028] 5.1. Sample loading: The sample box enters the cryogenic transfer channel through the airlock, and the gaseous nitrogen environment quickly cools the sample to the target temperature.

[0029] 5.2. Acoustic field activation: The piezoelectric array generates a standing wave acoustic field to capture and suspend the sample.

[0030] 5.3. Dynamic Transmission: The phase array adjusts the position of the sound field nodes, driving the sample to move at high speed in a jumping manner, and the AI algorithm corrects the trajectory in real time.

[0031] 5.4. Destination Docking: After the sample reaches the target location (such as a liquid nitrogen tank or a testing instrument), the acoustic field is turned off and the sample falls smoothly into the receiving container.

[0032] Comparison of technical advantages

[0033]

[0034] Key scientific basis

[0035] Acoustic radiation force formula:

[0036]

[0037] Where P is the sound pressure, A is the sample cross-sectional area, ρ is the medium density, c is the speed of sound, and α is a coefficient related to the sound field distribution. By increasing the sound pressure (e.g., 140dB) and optimizing the sound field distribution, the levitation force can be enhanced and the applicable sample range can be expanded. Cryobiology Theory:

[0038] The low temperature environment of gaseous nitrogen (-196°C) combined with rapid cooling causes the cells to enter a "vitrified" state, preventing ice crystals from piercing the cell membrane and significantly improving the survival rate after cryopreservation.

[0039] This patent achieves contactless transmission through acoustic levitation, uses gaseous nitrogen cryogenic medium to suppress ice crystal damage, and combines phase array collaborative control and modular design. While increasing the transmission speed by 5 times, it is compatible with existing biological sample library equipment and provides an innovative solution for high-throughput and high-activity processing of cell samples.

[0040] Core technology solutions

[0041] 1. Acoustic levitation device

[0042] 1.1 High-frequency piezoelectric transducer array

[0043] Device selection and layout:

[0044] Piezoelectric ceramic transducers (PZT-8 type) are used, and the array is arranged in a ring or linear shape and symmetrically distributed around the transmission channel to ensure uniform coverage of the sound field.

[0045] Frequency selection: 20-40kHz high-frequency sound waves can avoid shear damage to cells caused by low-frequency sound waves (such as <10kHz easily causes cavitation effect), and prevent energy loss caused by medium absorption in the high-frequency band (>50kHz).

[0046] Sound pressure level control: The power amplifier dynamically adjusts the sound pressure level to 130-140dB, ensuring that the acoustic radiation force is sufficient to suspend cell droplets or frozen samples with a diameter of 5-200μm.

[0047] 1.1.1 Device Selection and Performance Parameters

[0048] Material selection:

[0049] Piezoelectric ceramic model: PZT-8 (lead zirconate titanate), with high mechanical quality factor (Qm ≥ 1000) and low dielectric loss (tanδ ≤ 0.4%), suitable for high-frequency, high-power scenarios.

[0050] Substrate material: Alumina ceramic (Al2O3, purity ≥99.6%), thermal conductivity 28W / (m·K), ensuring heat dissipation performance. Key parameters:

[0051] Resonant frequency: Single transducer nominal frequency 30kHz, operating bandwidth ±2kHz (28-32kHz).

[0052] Sound pressure output: Single transducer maximum sound pressure level (SPL) 145dB (@30kHz, driving voltage 200Vpp).

[0053] Durability: Continuous working life ≥ 10,000 hours (@80% rated power).

[0054] 1.1.2 Array Layout and Structural Design

[0055] Arrangement:

[0056] Annular array: consists of 24 transducer units, evenly distributed on the outer wall of the transmission channel (diameter 50mm), forming an axisymmetric sound field.

[0057] Spacing optimization: The center distance between adjacent units is 6.5mm (about 1 / 2 wavelength, λ=11.3mm@30kHz, nitrogen sound speed 343m / s) to avoid energy cancellation caused by acoustic wave interference.

[0058] Mechanical structure:

[0059] Package design: The transducer is embedded in a fluororubber (FKM) sealing ring, with a protection level of IP68 and can adapt to temperature changes from -196°C to 25°C.

[0060] Heat dissipation solution: Micro heat pipes (3mm diameter) are integrated on the back of the substrate and connected to copper heat dissipation fins (surface area 120cm 2 ), temperature rise ≤15℃(@rated power).

[0061] 1.1.3 Driving Circuit and Control Logic

[0062] Power amplifier module:

[0063] Circuit topology: Class-D amplifier, efficiency ≥92%, output power 0-50W continuously adjustable.

[0064] Key components: GaN FET (model EPC2045), switching frequency 1MHz, supporting high-frequency PWM modulation.

[0065] Frequency synchronization mechanism:

[0066] Phase-locked loop (PLL) control: The main control chip (STM32H743) monitors the transducer impedance phase in real time, dynamically adjusts the drive frequency, and maintains the resonant state (phase difference Δφ≤5°).

[0067] Multi-channel synchronization: Synchronize the drive signals of 24 transducers via the CAN bus with a timing jitter of ≤10ns.

[0068] 1.1.4 Sound Field Calibration and Testing Methods

[0069] Calibration process:

[0070] 1.1.4.1. Scan the transducer surface vibration using a laser Doppler vibrometer (Polytec PSV-500) to ensure amplitude consistency (deviation ≤ ±5%).

[0071] 1.1.4.2. Sound pressure distribution measurement: Place a micro-microphone (GRAS 46BE) in the channel to generate a three-dimensional sound pressure contour map and calibrate the node position accuracy (±0.05mm).

[0072] Performance Verification:

[0073] Suspension force test: Use standard weights (0.1-10mg) to simulate the sample, measure the relationship between suspension force and sound pressure level, and fit the formula:

[0074] F=0.023×P 2 (F unit is mN, P unit is kPa, R 2 =0.998).

[0075] Frequency response test: sweep frequency 20-40kHz, record sound pressure level attenuation curve, -3dB bandwidth ≥ 4kHz.

[0076] 1.1.5 Reliability Enhancement Design

[0077] Low temperature adaptability:

[0078] Material thermal matching: The coefficient of thermal expansion (CTE) of the piezoelectric ceramic and the alumina substrate are matched (PZT-8 CTE = 7.2ppm / °C, Al2O3 CTE = 8.1ppm / °C) to avoid thermal stress cracking.

[0079] Wire reinforcement: The transducer electrode connection adopts silver-plated copper wire (diameter 0.2mm), the outer layer is covered with polyimide insulation layer, which is resistant to low temperature embrittlement.

[0080] Anti-interference design:

[0081] Electromagnetic shielding: The drive circuit is placed in an aluminum alloy shielding box (thickness 2mm), with MuMetal foil padding inside, and the radiation noise is ≤30dBμV / m.

[0082] Vibration isolation: The array bracket is installed with a silicone shock-absorbing pad (damping coefficient 0.15), and the amplitude during transmission is ≤1μm (@50mm / s speed).

[0083] Technical parameter summary table

[0084]

[0085] Through the above-mentioned refined design and strict parameter control, the array can stably generate high-intensity acoustic fields at extremely low temperatures, providing the core driving force for the contactless transmission of cell samples.

[0086] 1.2 Generation and Control of Standing Wave Sound Field

[0087] 1.2.1 Standing wave formation mechanism

[0088] 1.2.1.1 Principle of Sound Wave Reflection and Superposition

[0089] The high-frequency sound waves (28-32kHz) emitted by the piezoelectric transducer propagate in the transmission channel. After being reflected by the titanium alloy reflector (5mm thickness, surface roughness Ra≤0.1μm) on the top, they form a coherent superposition with the incident wave to generate a stable standing wave.

[0090] Wavelength calculation:

[0091] The speed of sound in nitrogen medium is c = 343m / sc = 343m / s, the frequency of sound wave is f = 30kHzf = 30kHz, and the wavelength is λ = c / f≈11.3mm.

[0092] The standing wave node spacing is λ / 2≈5.65mmλ / 2≈5.65mm, ensuring that the sample is suspended in the central node area.

[0093] 1.2.1.2 Sound Field Distribution Optimization

[0094] Finite element simulation: The sound field model was established using COMSOL Multiphysics, and the curvature of the reflector was optimized (radius of curvature R = 25 mm) to ensure that the deviation of the sound pressure distribution uniformity was ≤ ±3%.

[0095] Edge effect suppression: Cover the side walls of the transmission channel with sound-absorbing material (polyurethane foam, thickness 10mm, sound absorption coefficient α≥0.9@30kHz) to reduce sound wave scattering interference.

[0096] 1.2.2 Dynamic Adjustment System

[0097] 1.2.2.1 Feedback Control Architecture

[0098] Sensor configuration:

[0099] A laser displacement sensor (Keyence LK-G5000, resolution 0.01 μm) was used to monitor the sample position in real time with a sampling frequency of 1 kHz.

[0100] An array of sound pressure sensors (Bruel&Kjaer 4138-A-015) is embedded in the channel wall to measure the sound pressure level distribution.

[0101] Control algorithm:

[0102] PID closed-loop control: Dynamically adjust the transducer drive voltage based on the sample position error e(t)

[0103]

[0104] Parameters Kp=2.5, Ki=0.1Ki=0.1, Kd=0.05Kd=0.05.

[0105] Adaptive filtering: Uses LMS (least mean square) algorithm to eliminate environmental vibration noise, improving the signal-to-noise ratio by ≥20dB.

[0106] 1.2.2.2 Multimodal Sound Field Switching

[0107] Pattern Library Presets:

[0108]

[0109] Switching logic:

[0110] The user selects the sample type through the HMI interface, and the system automatically matches the sound field mode, with a switching time of ≤50ms.

[0111] 1.2.3 Phase Modulation and Node Shift

[0112] 1.2.3.1 Phase Difference Control Principle

[0113] Node movement formula:

[0114] The phase difference Δφ is introduced between adjacent transducer units, so that the node position of the synthetic sound field is translated along the channel axis.

[0115] Example: When Δφ=π / 2, Δx≈2.8mm.

[0116] Timing synchronization:

[0117] A 24-channel PWM signal is generated by an FPGA (model Xilinx Artix-7), with a phase resolution of 0.1° and a timing error of ≤1ns.

[0118] 1.2.3.2 Guaranteeing motion smoothness

[0119] S-curve acceleration and deceleration algorithm:

[0120] The sample acceleration changes according to an S-shaped curve (maximum acceleration amax = 500 mm / s2 amax = 500 mm / s2) to avoid oscillation caused by sudden changes in speed.

[0121] Trajectory prediction compensation:

[0122] Based on the feedforward control model, the sound field phase change is calculated in advance to compensate for the system response delay (delay time ≤ 5ms).

[0123] 1.2.4 Calibration and verification methods

[0124] 1.2.4.1 Sound Field Calibration Process

[0125] (1). No-load calibration:

[0126] A standard sound source (B&K 4220) is used to excite the sound field in the channel, and the microphone array measures the sound pressure distribution to generate a reference sound field map.

[0127] (2) Load testing:

[0128] Injection of simulated samples (polystyrene microspheres, density 1.05 g / cm 3 ) to verify that the deviation between the suspension position and the theoretical node is ≤±10μm.

[0129] 1.2.4.2 Dynamic performance test

[0130] Transmission speed test:

[0131] Fluorescently labeled HeLa cells were used as samples. The motion trajectory was recorded with a high-speed camera (Phantom VEO 410L, 10,000 fps). The error between the calculated actual speed and the set value was ≤±2%.

[0132] Stability verification:

[0133] After 24 hours of continuous operation, the monitoring node position drift is ≤±0.5μm and the sound pressure level fluctuation is ≤±0.5dB.

[0134] Technical parameter summary table

[0135]

[0136] Through precise standing wave acoustic field design and real-time dynamic control, this system can achieve lossless, high-speed transmission of cell samples in extremely low-temperature environments, while supporting flexible multi-modal switching to meet the application needs of complex biological sample libraries.

[0137] 2. Low temperature transmission channel

[0138] 2.1 Gaseous nitrogen low temperature environment design

[0139] Medium circulation system:

[0140] Gas source: Liquid nitrogen storage tank (-196℃) is converted into gaseous nitrogen by vaporizer and input into transmission channel through insulated pipeline (vacuum multi-layer insulation structure).

[0141] Flow control: The mass flow meter (MFC) accurately adjusts the gas flow rate (5-10L / min) to maintain the temperature gradient in the channel ≤2℃ / cm to avoid local overcooling that may cause sample freezing.

[0142] Temperature stability guarantee:

[0143] Distributed temperature control: The channel is embedded with platinum resistance temperature sensors (PT100, accuracy ±0.1°C), and data is fed back to the multi-segment PID controller in real time to independently adjust the heating / cooling power of each segment.

[0144] Anti-icing design: The inner wall of the channel is coated with a hydrophobic nano-coating (contact angle > 150°) to prevent condensed water from adhering to form an ice layer.

[0145] 2.1.1 Medium circulation system

[0146] 2.1.1.1 Gas source and vaporization device

[0147] Liquid nitrogen storage tank:

[0148] Volume: 100L, double-layer vacuum insulation structure (interlayer vacuum degree ≤ 10-3Pa), daily evaporation rate ≤ 0.5%.

[0149] Output pressure: 0.2-0.5MPa (adjustable), stable air supply through a pressure reducing valve (model Swagelok SS-4R3A).

[0150] Carburetor Design:

[0151] Material: 316L stainless steel, fin heat exchange structure (fin density 20 pieces / cm 2 ), liquid nitrogen vaporization efficiency ≥99.5%.

[0152] Vaporization capacity: 5-10L / min liquid nitrogen converted to gaseous nitrogen (temperature -150℃ to -196℃).

[0153] 2.1.1.2 Insulation Pipe Design

[0154] Multilayer vacuum insulation pipe:

[0155] Structure: The inner layer is a stainless steel bellows (diameter 10mm), the outer layer is a vacuum interlayer (vacuum degree ≤ 10-2Pa), and the middle layer is wrapped with 20 layers of aluminum foil + glass fiber composite reflective screen.

[0156] Heat leakage rate: ≤0.1W / m (@-196℃ ambient temperature difference).

[0157] Flange connection:

[0158] Adopt VCR metal sealing joint (material Cu / Ni alloy), leakage rate ≤1×10 -9 Pa·m 3 / s.

[0159] 2.1.1.3 Mass flow control

[0160] Flow meter selection:

[0161] Thermal mass flow meter (MFC, model Bronkhorst EL-FLOW Select), range 0-15 L / min, accuracy ±0.5% RD (full scale).

[0162] Control logic:

[0163] According to the temperature feedback in the channel (PT100 sensor), the flow valve opening is dynamically adjusted by the PID algorithm (proportional coefficient Kp = 1.2, integration time Ti = 30s) to maintain the temperature gradient ≤ 2°C / cm.

[0164] 2.1.2 Temperature stability guarantee

[0165] 2.1.2.1 Distributed Temperature Monitoring

[0166] Sensor arrangement:

[0167] A PT100 platinum resistance sensor (accuracy ±0.1°C) is arranged every 10 cm in the axial direction of the channel, and a sensor is arranged in each of the four quadrants in the radial direction, forming a 5×4=20-point monitoring network.

[0168] Data collection:

[0169] A 24-bit ADC module (ADS1248) is used with a sampling rate of 100 Hz and RS-485 transmission to the main control unit.

[0170] 2.1.2.2 Multi-zone PID temperature control

[0171] Partitioning strategy:

[0172] The transmission channel is divided into five independent temperature-controlled sections (each 20 cm long), each equipped with an independent heating wire (made of nickel-chromium alloy, with a resistance of 10Ω / m) and a cooling valve.

[0173] Control parameters:

[0174] Heating power: 0-50W / segment (PWM adjustment, resolution 0.1%).

[0175] Cooling valve response time: ≤50ms, temperature fluctuation suppressed to ±0.5℃.

[0176] 2.1.2.3 Anti-icing coating

[0177] Coating material:

[0178] Hydrophobic nano coating (base material SiO2, modified perfluorooctyltriethoxysilane), contact angle>150°, surface energy≤20mN / m. Coating process:

[0179] Plasma enhanced chemical vapor deposition (PECVD), film thickness 500nm, adhesion ≥5B (ASTM D3359 standard).

[0180] 2.1.3 Sample cryogenic protection mechanism

[0181] 2.1.3.1 Premixing of vitrification protective agent

[0182] Protective agent formula:

[0183] VS55 solution (30% w / v): ethylene glycol (15%), dimethyl sulfoxide (15%), sucrose (0.5 M), pH 7.4 (HEPES buffer).

[0184] Mixing device:

[0185] Microfluidic chip (channel width 200 μm), sample and protective agent were mixed in a volume ratio of 1:3, and the mixing efficiency was ≥95%.

[0186] 2.1.3.2 Helium doping optimization

[0187] Doping ratio:

[0188] Helium (He) accounts for 1% (volume fraction) and is precisely controlled by a mass flow meter (MFC), increasing the thermal conductivity of the mixed gas to 0.18W / (m·K).

[0189] Cooling rate:

[0190] The sample cooling rate is >1000℃ / min (it only takes 10.5 seconds for a Hela cell droplet to cool from 25℃ to -150℃), and the ice crystal volume accounts for <0.1%.

[0191] Key Parameters Table

[0192]

[0193] Technological advantages

[0194] (1) Low temperature uniformity: Multi-zone PID temperature control combined with a 20-point monitoring network ensures that the sample is in the glass transition window (-150°C to -196°C) throughout the entire process.

[0195] (2) Anti-ice crystal damage: Helium doping + ultra-fast cooling, the ice crystal inhibition rate is increased by 90% compared with traditional liquid nitrogen immersion.

[0196] (3) System reliability: vacuum insulation + metal seal, continuous operation for 72 hours without freezing or leakage.

[0197] This design achieves efficient protection and stable transmission of cell samples at extremely low temperatures through precise gas source control, distributed temperature control and active antifreeze strategies.

[0198] 2.2 Sample low temperature protection mechanism

[0199] Vitrification Assistance:

[0200] Before entering the transmission channel, the sample is premixed with a vitrification protective agent (such as VS55 solution) and combined with rapid cooling by gaseous nitrogen (cooling rate >1000℃ / min) to make the inside and outside of the cell reach a glassy state at the same time, with the volume of ice crystals accounting for <0.1%.

[0201] Low temperature suspension medium optimization:

[0202] By adding 0.1%-1% helium (He) to gaseous nitrogen and utilizing its high thermal conductivity (λ=0.152W / m·K), the heat exchange of the sample is accelerated, shortening the cooling time by more than 30%.

[0203] 2.2.1 Vitrification technology

[0204] 2.2.1.1 Protective agent formulation and pretreatment

[0205] Recipe composition:

[0206] Basal solution: Phosphate buffered saline (PBS, pH 7.4) was used as a carrier.

[0207] Osmoprotectants: ethylene glycol (EG, 15% v / v) and dimethyl sulfoxide (DMSO, 15% v / v) reduce intracellular ice crystal formation.

[0208] Non-permeable protective agents: sucrose (0.5 M) and polyethylene glycol (PEG 8000, 5% w / v), stabilize the cell membrane and inhibit the growth of extracellular ice crystals.

[0209] Mixing process:

[0210] Microfluidic mixing chip: Sample and protective agent are laminarly mixed in a microchannel (width 200 μm) at a volume ratio of 1:3, with a mixing efficiency ≥ 98% (based on fluorescence tracer testing).

[0211] Gradient loading: Increase the protective agent concentration in three steps (5%→10%→15%), with an interval of 2 minutes between each step to avoid damage to cells due to sudden changes in osmotic pressure.

[0212] 2.2.1.2 Rapid Cooling and Glass Formation

[0213] Cooling rate control:

[0214] The time required to cool the sample from 25°C to -150°C is ≤10 seconds, and the average cooling rate is >1000°C / min (verified by the high-speed infrared thermal imager FLIR X8580SC).

[0215] Critical cooling rate: According to the formula (Tg\) is the glass transition temperature, T0 is the initial temperature, and τ is the characteristic time). In this system, Rc is ≈ 800℃ / min, and the actual rate meets the standard.

[0216] Ice Crystal Inhibition Effect:

[0217] Observation by cryogenic scanning electron microscopy (Cryo-SEM) showed that the average diameter of ice crystals was ≤50 nm and the volume proportion was <0.1% (the diameter of ice crystals in the control group using traditional slow freezing was ≥500 nm and the proportion was >5%).

[0218] 2.2.2 Optimization of low-temperature transmission environment

[0219] 2.2.2.1 Helium doping to enhance thermal conductivity

[0220] Doping ratio and effect:

[0221] When 1% by volume of helium (He) is added to gaseous nitrogen, the thermal conductivity of the mixed gas increases from 0.152 W / (m·K) to 0.18 W / (m·K) (+18%).

[0222] Heat exchange time constant: After helium doping, τ is reduced from 1.2 seconds to 0.9 seconds, and the cooling rate is increased by 25%. Uniformity assurance:

[0223] The gas mixer adopts a vortex structure (Reynolds number Re>4000) to ensure that the deviation of helium distribution uniformity is ≤±2%.

[0224] 2.2.2.2 Low-temperature suspension medium design

[0225] Gaseous nitrogen flow field optimization:

[0226] Laminar flow control: a honeycomb rectifier (aperture 3 mm) is set in the channel, the airflow Reynolds number Re<2000, and the turbulence intensity ≤1%.

[0227] Humidity control: dew point temperature ≤ -70℃ (drying by molecular sieve adsorption) to prevent water vapor from condensing into ice crystals.

[0228] 2.2.3 Thawing and resuscitation compatibility design

[0229] 2.2.3.1 Rapid rewarming module

[0230] Micro Thin Film Heaters:

[0231] Integrated at the end of the transmission channel, using aluminum nitride ceramic substrate (thermal conductivity 180W / (m·K)), power density 50W / cm 2 , can be heated to 25℃ within 0.1 seconds.

[0232] Thawing curve: The sample takes ≤3 seconds to rise from -196℃ to 4℃, and the reheating rate is 4000℃ / min (to avoid devitrification damage). Gradient dilution protective agent:

[0233] After rewarming, the protective agent concentration was diluted in three steps of 1:5:10 (15%→10%→5%→0%) using a microfluidic chip, with an interval of 30 seconds between each step. The cell survival rate was ≥98%.

[0234] 2.2.3.2 Verification of resuscitation activity

[0235] Detection indicators:

[0236] Membrane integrity: Trypan blue staining method, stain rejection rate ≥97%.

[0237] Metabolic activity: Mitochondrial function was detected by MTT assay, and the OD value (570 nm) was ≥ 95% of that in the control group.

[0238] Functional recovery: The Hela cell attachment rate (after 24 hours) was ≥90%, and the proliferation rate had no significant difference compared with the non-frozen group (p>0.05, t-test).

[0239] Key Parameters Table

[0240]

[0241] Technological advantages

[0242] (1) Nearly zero damage to ice crystals: Vitrification combined with ultra-fast cooling reduces the volume of ice crystals to <0.1%, significantly superior to traditional methods. (2) Full process compatibility: Closed-loop protection from freezing, transfer to thawing improves survival rate by 5-8% compared to existing technologies.

[0243] (3) Fast and reversible operation: supports millisecond-level freezing-rewarming switching to meet the dynamic access requirements of high-throughput sample libraries.

[0244] This mechanism systematically solves the problem of maintaining the activity of cell samples during low-temperature transmission through gradient protective agent loading, helium-enhanced heat transfer and precise retemperature control, providing a full-cycle protection solution for biological sample libraries.

[0245] 3. Modular compatible design

[0246] 3.1 Mechanical interface standardization

[0247] Adapter structure:

[0248] Magnetic docking module: The transmission channel outlet is integrated with a NdFeB permanent magnet (grade N52), which is adsorbed to the magnetic stainless steel ring of the sample box holder with an alignment accuracy of ±0.2mm.

[0249] Buckle quick release mechanism: Made of PEEK buckle, supports quick positioning of 96-well plates and 384-well plates that meet SBS standards (hole spacing 9mm, row spacing 9mm).

[0250] Multi-specification compatible solutions:

[0251] Provides replaceable acoustic field reflectors (e.g., apertures from 1mm to 5mm) to accommodate different containers such as 0.5mL cryotubes and 5mL centrifuge tubes, with a switching time of <10 seconds.

[0252] 3.2 Software and Communication Protocol

[0253] Open control architecture:

[0254] Hardware interface: supports RS-485, CAN bus and EtherCAT protocols, and can be directly connected to the PLC or SCADA system of the biological sample library.

[0255] Software SDK: Provides API function library (C++ / Python) to support user-defined transmission paths, speed curves, and temperature parameters.

[0256] Data interaction module:

[0257] The built-in OPC UA server uploads sample ID, transmission status, temperature and humidity data to the cloud database in real time. It is compatible with mainstream sample management software such as LabWare LIMS and FreezerPro.

[0258] 4. High-speed transmission optimization technology

[0259] 4.1 Acoustic Wave Phased Array Cooperative Control

[0260] Phase modulation principle:

[0261] Multiple transducers form a phased array, and the position of the sound field node is shifted by adjusting the sound wave emission timing (phase difference Δφ) of each unit.

[0262] Jump transmission: The nodes move at a step distance of 0.5-2mm / time and a frequency of 100Hz. The sample is driven by the acoustic radiation force to "jump" synchronously with an average speed of 50mm / s.

[0263] Motion smoothness guarantee: S-curve acceleration and deceleration algorithm is used to avoid sample oscillation caused by sudden stops and starts.

[0264] 4.2 AI Dynamic Trajectory Prediction

[0265] Algorithm framework:

[0266] Based on the fusion model of convolutional neural network (CNN) and long short-term memory network (LSTM), the input parameters include real-time airflow velocity, temperature distribution, sample quality and historical motion trajectory.

[0267] Control strategy:

[0268] Disturbance compensation: Predicts airflow turbulence (such as vortex position) and adjusts the sound field phase in advance, with the offset error controlled within ±5μm.

[0269] Adaptive learning: The system continuously optimizes model weights during operation to adapt to different laboratory environments (such as altitude and humidity differences).

[0270] 5. System integration and verification

[0271] 5.1 Performance Test Data transmission speed: HeLa cell droplets (100 μm diameter) at -180°C have an average speed of 52.3 mm / s (standard deviation ±1.2 mm / s).

[0272] Survival rate comparison:

[0273] Transmission method Survival rate (after 24 hours) Ice crystal damage rate Mechanical gripper 91.5％ 8.2％ This patented system 99.1％ |0.3％

[0274] 5.2 Compatibility Verification

[0275] Device compatibility: Successfully connects to mainstream sample libraries such as Thermo Fisher SampleMatrix and Brooks BioStore III without hardware modification, with a 100% communication protocol match rate.

[0276] Scalability testing: By replacing the reflector and adapter, it supports multi-scale sample transmission from single cells (10μm) to tissue sections (5mm).

[0277] Key parameter settings

[0278] (1) Sound field stability:

[0279] Problem: The sound field is easily disturbed and unstable by airflow during high-speed transmission.

[0280] Solution: Introduce closed-loop feedback control and combine it with Kalman filter to eliminate noise interference.

[0281] (2) Reliability of electronic components in low temperature environments:

[0282] Problem: -196°C causes sensor and circuit failure.

[0283] Solution: Use low-temperature enhanced components (such as SiC semiconductors) and local heating to maintain the control module temperature >-40°C.

[0284] (3) Multi-physics field coupling optimization:

[0285] Problem: The sound field, temperature field, and flow field affect each other.

[0286] Solution: Based on COMSOL Multiphysics simulation, a multi-field coupling parameter optimization database is preset.

[0287] Through high-frequency acoustic levitation, gaseous nitrogen cryogenic control, phased array coordinated acceleration, and a modular plug-and-play design, this system systematically addresses the challenges of damage, efficiency, and compatibility in cell sample transfer. Experimental data demonstrates that its speed and survival rate significantly outperform conventional technologies, and it possesses the potential for large-scale commercial application.

[0288] Originality and beneficial effects

[0289] 1. Originality

[0290] 1. Fusion of non-contact acoustic levitation and cryogenic transmission

[0291] A groundbreaking design combines high-frequency acoustic levitation technology (30kHz) with an ultra-low temperature nitrogen atmosphere (-196°C), enabling the first high-speed cryo-transfer of cell samples without mechanical contact, breaking through the bottleneck of damage caused by traditional mechanical grippers or liquid nitrogen immersion. Acoustic levitation completely avoids mechanical damage, increasing sample survival rates by over 7%.

[0292] Technological cross-innovation: Dynamically control the position of the sound field nodes through the phase array, combined with AI trajectory prediction, to solve the problem of suspension stability under low-temperature airflow disturbances (patented unique algorithm, core patent has been applied for).

[0293] 2. Helium doping to enhance heat transfer technology

[0294] Unique formula: Adding 1-2% helium (He) to gaseous nitrogen significantly improves thermal conductivity (+18%), enabling ultra-fast sample cooling (>1000°C / min), and improving ice crystal suppression by 90% compared to traditional methods (supported by experimental data).

[0295] Synergistic protection mechanism: The synergistic effect of vitrification protective agent premixing and helium cooling forms "chemical-physical" dual protection, which is the first of its kind in the world.

[0296] 3. Modular plug-and-play interface

[0297] Standardized adaptation: The magnetic mechanical interface and open communication protocol (RS-485 / Modbus) are compatible with more than 90% of commercial biobank equipment, without the need for hardware modification (compared to existing technologies that require customized docking).

[0298] 4. Efficiency breakthrough: The transmission speed is 5 times that of traditional systems, meeting the needs of high-throughput sample libraries.

[0299] 2. Beneficial Effects

[0300] 1. Sample activity is significantly improved

[0301] Breakthrough in survival rate: cell survival rate after transfer ≥99.1% (traditional method ≤92.4%), ice crystal damage rate reduced to 0.3% (control group ≥7.8%).

[0302] Functional integrity: After rewarming, the cell adhesion rate and proliferation ability showed no statistical difference compared with the untreated group (p>0.05), meeting the requirements of clinical application.

[0303] 2. Revolutionary improvement in transmission efficiency

[0304] Speed advantage: The transmission speed reaches 50mm / s (traditional mechanical transmission is 10mm / s), the efficiency is increased by 5 times, and the daily sample processing volume is increased from 500 to 2,500.

[0305] High-throughput support: supports continuous and uninterrupted transmission, with a system mean time between failures (MTBF) greater than 10,000 hours.

[0306] 3. Compatibility and cost advantages

[0307] Seamless integration: Compatible with mainstream sample libraries such as Thermo Fisher and Brooks, reducing user upgrade costs by 70% (compared to full system replacement).

[0308] Energy consumption optimization: The power consumption of the acoustic suspension unit is ≤50W, which saves 40% energy compared with the traditional liquid nitrogen pump system.

[0309] 4. Full process automation and traceability

[0310] Intelligent control: AI algorithms optimize transmission parameters in real time, reducing manual intervention and operational error rates to below 0.1%.

[0311] Data closed loop: The OPC UA protocol enables full-process recording of sample ID, temperature, and transmission status, and supports blockchain traceability (compliant with FDA 21CFR Part 11 standards).

[0312] Quantitative advantages compared to existing technologies

[0313]

[0314] Precision medicine: Suitable for low-temperature transportation of precious samples such as CAR-T cells and stem cells to ensure therapeutic activity.

[0315] Biopharmaceuticals: Rapid packaging and transmission of high-throughput drug screening samples to improve R&D efficiency.

[0316] Space biology: Achieving contactless manipulation of cell samples in a microgravity environment. This patented technology addresses the three core challenges of cryogenic cell sample transfer: damage, efficiency, and compatibility. Its innovative technology and significant benefits offer a disruptive solution for automated and standardized upgrades in biobanking, with enormous market potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0317] Figure 1 : Main view of the overall structure of the system. The figure shows components such as the liquid nitrogen storage tank, vaporizer, insulated pipe, transmission channel (acoustic levitation + cryogenic transmission), and marks the liquid nitrogen flow path (blue dotted line) and control signal flow (red solid line). The dimensional parameters of the transmission channel are also marked in detail. The control system includes an AI module and is connected to other parts through a modular interface (magnetic attraction / communication). The parameters of the piezoelectric transducer array are also clearly marked.

[0318] Figure 2 : Top view of the cross section of the transmission channel (partially enlarged). The details of the high-frequency piezoelectric transducer array (24 units arranged in a ring) are shown. The figure clearly marks the inner diameter of the transmission channel of 50mm, the flow direction of gaseous nitrogen, the center of sample suspension (node position, suspension height 1mm), and the inner wall of the hydrophobic coating (contact angle <150°). In addition, key parameters are also marked, including the transducer spacing of 6.5mm (center-to-center distance between adjacent units), the sound pressure level of 140dB@30kHz, and the gaseous nitrogen flow rate of 8L / min.

[0319] Figure 3A 3D exploded view of the acoustic levitation module shows the structural relationships and assembly sequence of the various components. The piezoelectric ceramic, alumina substrate, micro heat pipes, and copper fins form the axial heat dissipation path. A fluororubber sealing ring wraps the entire transducer unit and is secured to the transmission channel wall via threads.

[0320] Figure 4 Side view of the cryogenic control system. This shows the connection between the PT100 sensor and the multi-zone PID controller, as well as the layout of the heating wire, air cooling nozzle, and honeycomb rectifier. The temperature control system is divided into five sections, each 20 cm, and the heating wire power density can be adjusted from 0 to 2.5 W / cm 2 The voltage is adjusted by PWM.

[0321] Figure 5 : Detail of the modular interface. Showing its connection with the 96-well plate positioning slot and RS-485 communication interface. The magnetic attraction force is 5N, the communication rate is 115200bps, and the bit error rate is less than 10 -6 , ensuring high precision and reliability.

[0322] Figure 6 Schematic diagram of the annular array layout (cross-sectional top view). This shows 24 PZT-8 piezoelectric ceramic transducer units evenly distributed around a 50mm diameter transmission channel, with a 6.5mm center-to-center spacing between adjacent units to prevent acoustic wave interference.

[0323] Figure 7 Schematic diagram of the transducer package structure (3D cross-section). This shows the detailed layout of each component. A fluororubber sealing ring surrounds the exterior, providing IP68 protection and an operating temperature range of -196°C to 80°C. The piezoelectric ceramic is bonded to an alumina substrate, with copper electrodes soldered to the back. Micro heat pipes are embedded in the substrate and connected to copper heat sink fins, reducing temperature rise through phase change heat transfer.

[0324] Figure 8 Schematic diagram of the heat dissipation system (side view). This diagram shows the heat dissipation path of the transducer unit. The transducer unit consists of a piezoelectric ceramic plate and an alumina substrate. Micro heat pipes connect the substrate and flow to copper cooling fins. The direction of nitrogen flow is also indicated. The heat dissipation path is clearly marked. The heat pipe heat transfer power is ≥15W, and the temperature rise on the fin surface is ≤15°C at a wind speed of 2m / s.

[0325] Figure 9Schematic diagram of anti-interference and vibration isolation (cross-section of the mounting bracket). The diagram shows the structure and layout of the transducer array bracket, silicone shock-absorbing pads, and mounting bolts. The bracket is made of 5mm thick aluminum alloy, the silicone shock-absorbing pads are 3mm thick and have a damping coefficient of 0.15. The bolts are M3 in size, spaced 20mm apart, and have a preload of 5N·m to ensure mechanical stability. The silicone pads effectively isolate vibrations between the bracket and the transmission channel, attenuating amplitudes by over 90%.

[0326] Figure 10 A side view of the overall system shows key components such as the liquid nitrogen storage tank, vaporizer, insulated piping, mass flow meter, control valve, and nitrogen recovery line.

[0327] Figure 11 A cross-section of an insulated pipe. Details are shown, including the outer stainless steel protective shell, vacuum interlayer, reflective screen, inner corrugated stainless steel pipe, and nitrogen flow. The thermal resistance calculation formula and parameters are also noted.

[0328] Figure 12 Schematic diagram of the transmission channel temperature control network. This diagram shows an axially expanded top view. The diagram includes five sections, each equipped with a heating wire. Each section has four PT100 sensors, for a total of 20 sensors. In the control logic, the PID parameters are: Kp = 1.2, Ki = 0.05, Kd = 0.02, and the heating wire power density range is 0-2.5W / cm 2 , controlled by PWM duty cycle 0-100%.

[0329] Figure 13 Schematic diagram of the anti-icing coating's microstructure. The image shows the transmission channel's inner wall, made of 316L stainless steel, covered with a 500nm-thick SiO2-based hydrophobic nanocoating. The surface microstructure features an array of nanocones with a height of 200nm and a spacing of 50nm. Performance parameters are also noted, including a contact angle of 152° and an ice adhesion of ≤5kPa.

[0330] Figure 14 Control system flow chart. This systematically demonstrates the medium circulation, thermal management, and control logic of the gaseous nitrogen cryogenic environment, providing reliable technical support for the cryogenic transport of cell samples. DETAILED DESCRIPTION

[0331] Example 1: System Architecture and Standard Operating Procedures

[0332] 1. System hardware configuration

[0333] 1.1 Acoustic Levitation Module

[0334] Piezoelectric transducer array: 24 PZT-8 piezoelectric ceramic units, arranged in a ring on the outer wall of a 50mm diameter transmission channel, with a driving frequency of 30kHz and a sound pressure level of 140dB.

[0335] Reflector: Titanium alloy, surface polished to Ra≤0.1μm, curvature radius 25mm, distance from transducer 10mm.

[0336] Control circuit: Class-D power amplifier (output power 0-50W / unit), STM32H743 main control chip, supports multi-channel synchronous drive.

[0337] 1.2 Low temperature transmission channel

[0338] Structure: Double-layer vacuum insulated stainless steel tube (inner diameter 50mm, length 2m), with the inner wall coated with a hydrophobic nano-coating (contact angle >150°).

[0339] Temperature control system: 5 independent temperature control sections, each section integrates PT100 sensor, nickel-chromium heating wire (10Ω / m) and air-cooled nozzle, PID algorithm maintains -196℃±0.5℃.

[0340] Gas supply: Liquid nitrogen storage tank (100L) outputs gaseous nitrogen (flow rate 8L / min) through a vaporizer, and 1% helium is added to improve thermal conductivity.

[0341] 1.3 Modular Interface

[0342] Mechanical interface: Magnetic adapter (N52 NdFeB magnet), compatible with SBS 96-well plates (hole pitch 9 mm), positioning accuracy ±0.2 mm.

[0343] Communication interface: RS-485 bus, supports Modbus protocol, and real-time data interaction with third-party sample libraries (such as Brooks BioStoreIII).

[0344] 2. Standard operating procedures

[0345] 2.1 Sample preprocessing

[0346] Step 1: Vitrification Protectant Loading

[0347] A microfluidic chip was used to mix the cell sample (eg, Hela cell suspension) with the VS55 protective agent at a volume ratio of 1:3, and the gradient loading time was 6 minutes.

[0348] After mixing, the samples were sealed in standard cryopreservation tubes (0.5 mL), marked with ID and entered into the database.

[0349] 2.2 System startup and initialization

[0350] Step 2: Establish a low temperature environment

[0351] Open the liquid nitrogen storage tank, adjust the pressure reducing valve to an output pressure of 0.3 MPa, and inject gaseous nitrogen into the transmission channel at a flow rate of 8 L / min.

[0352] Multi-zone PID temperature control was started, and the channel temperature stabilized to -196℃±0.5℃ within 10 minutes.

[0353] 2.3 Sample loading and transmission

[0354] Step 3: Sonic Levitation Activation

[0355] The sample box is sent into the transmission channel through the airlock. The system automatically detects the sample position and activates acoustic levitation (sound pressure level 140dB).

[0356] The laser displacement sensor provides real-time feedback of sample coordinates, and the PID algorithm dynamically adjusts the sound field intensity to ensure a levitation height of 1.0mm±0.05mm.

[0357] 2.4 High-speed transmission control

[0358] Step 4: Phased Array Collaborative Acceleration

[0359] The transducer phase array adjusts the acoustic field node position according to the preset step size (1 mm / step) and frequency (100 Hz), driving the sample to move at a speed of 50 mm / s.

[0360] The AI trajectory prediction model (CNN-LSTM fusion network) analyzes airflow disturbances in real time and dynamically corrects the phase difference Δφ (resolution 0.1°).

[0361] 2.5 End point reception and thawing

[0362] Step 5: Sample Uninstallation

[0363] When the sample reaches the target location (such as the inlet of the liquid nitrogen tank), the acoustic field is turned off, and the sample falls smoothly into the receiving container via the pneumatic slide.

[0364] If thawing is required, start the end aluminum nitride film heater (power density 50W / cm 2 ), heat to 25°C within 1 second, and gradually dilute the protective agent.

[0365] Example 2: Extended Application - Large Volume Tissue Slice Transport

[0366] 1. Hardware adaptation and adjustment

[0367] 1.1 Replacement of sound field reflector

[0368] Replaced with a reflector with a standard aperture of 5 mm, suitable for 5 mL centrifuge tubes, and supports tissue sections (size ≤ 5 mm 3 )transmission.

[0369] Adjust the sound wave frequency to 25kHz and increase the sound pressure level to 145dB to enhance the levitation force.

[0370] 2. Operation parameter optimization

[0371] 2.1 Transmission speed adjustment

[0372] Due to the increase in sample mass (≤50 mg), the transmission speed was reduced to 20 mm / s, and the phase step was adjusted to 0.5 mm / step.

[0373] The AI model switches to "large mass mode," adds an inertia compensation algorithm, and controls trajectory deviation to ±0.1mm.

[0374] 2.2 Enhanced low temperature protection

[0375] The helium doping ratio is increased to 2%, and the cooling rate is >1200℃ / min to ensure uniform vitrification inside the tissue.

[0376] The rewarming phase is extended to 5 seconds to avoid structural damage caused by thermal stress.

[0377] Key operating parameters table

[0378]

[0379] Verification Tests and Results

[0380] 1. Transmission efficiency test

[0381] Test conditions: Continuous transmission of 100 HeLa cell samples (100 μm in diameter) at an ambient temperature of -180°C.

[0382] result:

[0383] The average transmission speed was 52.3 mm / s (standard deviation ±1.2 mm / s), and the total transmission time was 19.1 seconds per sample.

[0384] The control group (mechanical gripper) had a transmission speed of 10 mm / s and took 95.5 seconds per sample.

[0385] 2. Cell Viability Verification

[0386] Detection method: Trypan blue staining combined with MTT metabolic activity detection.

[0387] result:

[0388]

[0389] 3. Compatibility Verification

[0390] Compatible equipment: Thermo Fisher SampleMatrix, Hamilton MLP, Brooks BioStore III.

[0391] result:

[0392] The mechanical docking success rate is 100%, and the communication protocol matching rate is 100%.

[0393] The error rate of sample ID identification and database synchronization is 0%.

[0394] Maintenance and Calibration Guide

[0395] 1. Daily maintenance

[0396] Acoustic array calibration: Transducer amplitude consistency is checked monthly using a laser Doppler vibrometer. Recalibration is performed if the deviation is >±5%. Hydrophobic coating regeneration: Plasma cleaning (Ar gas, power 100W, 5 minutes) is performed every 6 months to restore the contact angle to >150°.

[0397] 2. Troubleshooting

[0398] Low temperature sensor failure: Check the wire connection. If the PT100 resistance is abnormal (>110Ω or <80Ω@-196℃), replace the low temperature enhanced sensor.

[0399] Sound field instability: Restart the PID control module, check the phase synchronization signal, and reload the sound field model library if necessary.

[0400] This specific implementation fully demonstrates the system's practical construction and operation methods through modular hardware configuration, standardized operating procedures, and expanded application adaptation. Experimental data validates its significant advantages in transmission efficiency, sample activity, and compatibility, providing a feasible solution for the automated upgrade of biobanks.

[0401] Example 3: System Architecture and Workflow

[0402] 1. Acoustic levitation module:

[0403] It consists of a piezoelectric ceramic array, a reflector and a resonant cavity, with a sound wave frequency of 30kHz, a sound pressure level of 140dB and a suspension height of 0.5-2mm.

[0404] After the sample passes through the airlock and enters the transmission channel, the acoustic field is automatically activated and locks the sample position.

[0405] 2. Maintain low temperature environment:

[0406] The outer wall of the channel adopts a vacuum insulation layer, and low-temperature nitrogen (flow rate 5L / min) is introduced into the interior. The temperature sensor provides real-time feedback to the PID controller with a fluctuation range of ±1°C.

[0407] 3. Modular interface implementation:

[0408] Mechanical interface: Adapts to SBS standard sample box holder and supports automatic alignment calibration.

[0409] Software interface: Provides SDK development kit, supports LabVIEW or Python script calling transmission instructions.

[0410] 4. High-speed transmission test:

[0411] Taking Hela cell samples as an example, a uniform transmission speed of 50 mm / s was achieved at -180°C, with a survival rate of ≥99% (the survival rate of the control group with mechanical transmission was 92%).

[0412] Example 4: Compatibility extension solution

[0413] 1.Multi-specification adapters:

[0414] Provides replaceable acoustic field reflectors to accommodate sample tubes of different sizes (e.g., 0.5 mL cryo tubes to 5 mL centrifuge tubes).

[0415] 2. Low temperature-normal temperature switching module:

[0416] The integrated micro-heating element supports rapid thawing of samples when transferred from the low-temperature storage to the room-temperature workstation (heating rate 10°C / s).

Claims

1. An acoustic suspension low-temperature transmission system for cell samples, characterized in that: include: High-frequency piezoelectric transducer array, composed of multiple piezoelectric ceramic units, with an operating frequency range of 20-40kHz and a sound pressure level of ≥130dB, is used to generate a standing wave sound field in the transmission channel to achieve non-contact suspension of the sample; The cryogenic transmission channel is filled with gaseous nitrogen and maintains a low-temperature environment of -150°C to -196°C. The inner wall of the channel is coated with a hydrophobic nano-coating to inhibit ice formation. Modular interfaces, including magnetic mechanical adapters and open communication protocols, are compatible with standard biobanking equipment; The control system integrates a phased array driving algorithm and an AI trajectory prediction module to dynamically adjust the sound field parameters to achieve high-speed transmission of samples.

2. The system according to claim 1, wherein: The high-frequency piezoelectric transducer array is arranged in a circular or linear symmetrical manner, and the spacing between adjacent units is 1 / 2 wavelength (λ / 2), where λ is the wavelength of the sound wave in the nitrogen medium.

3. The system according to claim 1, wherein: The gaseous nitrogen in the low-temperature transmission channel is doped with 1-2% by volume of helium (He) to increase the thermal conductivity to above 0.18 W / (m·K).

4. The system according to claim 1, wherein: The modular interface's mechanical adapter supports SBS standard sample box sizes, and communication protocols include RS-485, CAN bus, or EtherCAT.

5. The system according to claim 1, wherein: The control system includes: PID feedback module, which monitors the sample position in real time through a laser displacement sensor and dynamically adjusts the transducer drive voltage; The phase coordination module generates multi-channel PWM signals through FPGA to control the movement of the sound field nodes in 0.5-2mm steps; The AI trajectory prediction module compensates for airflow disturbances based on the CNN-LSTM fusion model, with a trajectory error of ≤±0.1mm.

6. The system according to claim 1, wherein: The hydrophobic nanocoating has a contact angle greater than 150° and a surface energy less than or equal to 20 mN / m and is prepared by a plasma enhanced chemical vapor deposition (PECVD) process.

7. The system according to claim 1, wherein: The invention also includes a vitrification protective agent premixing module, wherein the protective agent comprises ethylene glycol (15% v / v), dimethyl sulfoxide (15% v / v) and sucrose (0.5 M), which is mixed with the sample in a volume ratio of 1:3 through a microfluidic chip.

8. The system according to claim 1, wherein: The transmission channel is divided into multiple independent temperature control sections, each section integrates a heating wire and a PT100 sensor, and a multivariable PID algorithm is used to maintain temperature fluctuation ≤±0.5°C.

9. A method for low-temperature transmission of cell samples, using the system according to any one of claims 1 to 8, characterized in that: The following steps are involved: The sample is mixed with a vitrification protective agent and encapsulated; Activate acoustic levitation to immobilize the sample contactlessly in a -196°C gaseous nitrogen environment; The phase array is used to control the position of the acoustic field node and drive the sample to transmit at a speed of 50 mm / s. After reaching the target position, the acoustic field is turned off and the sample falls into the receiving container or rapid rewarming is initiated.

10. The method according to claim 9, characterized in that The rapid reheating is achieved by an aluminum nitride film heater, with a heating rate of ≥4000°C / min, and the protective agent is gradiently diluted after reheating.

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