Harvard Apparatus Homeothermic Blanket System for Small to Large Laboratory Animals

Overview

The Harvard Apparatus Homeothermic Blanket System is an engineered thermal regulation solution designed specifically for maintaining normothermia during acute in vivo experiments involving small to large laboratory animals. Operating on a closed-loop proportional feedback principle, the system continuously monitors core body temperature via a calibrated thermistor probe and dynamically modulates low-voltage DC power supplied to a highly flexible, insulated heating element embedded within the blanket. This real-time, analog-controlled thermal management avoids on/off switching artifacts—critical when interfacing with high-gain electrophysiological recording systems such as patch-clamp amplifiers, EEG/ECG signal conditioners, or intracranial pressure transducers. The system’s architecture ensures minimal electromagnetic interference (EMI), enabling stable acquisition of microvolt-level biological signals without contamination from thermal control circuitry.

Key Features

• Proportional temperature control algorithm eliminates thermal overshoot and cycling, delivering stable thermal maintenance within ±0.2 °C of setpoint under typical surgical conditions.
• Two interchangeable probe configurations: flexible epoxy-encapsulated thermistor (2 mm diameter, 100 mm length) optimized for rodents and larger mammals; rigid stainless-steel probe (1.6 mm diameter) suited for precise rectal placement in mice, rats, rabbits, cats, and dogs.
• Three anatomically scaled blanket sizes—Small (15 × 20 cm), Medium (45 × 70 cm), and Large (60 × 90 cm)—allow secure, conformal wrapping without constriction or thermal bridging.
• Electrically floating heating element with front-panel grounding switch; configurable isolation supports compliance with IEC 61010-1 safety requirements for biomedical instrumentation.
• Front-panel LCD displays real-time measured core temperature (35–40 °C range); horizontal LED bar graph provides immediate visual feedback on relative power delivery to the blanket.
• Low-noise electronic design validated for use alongside sensitive recording platforms—including Axon Instruments Digidata, ADInstruments PowerLab, and Blackrock Microsystems neural data acquisition systems.

Sample Compatibility & Compliance

The system accommodates a broad spectrum of species used in preclinical research, including adult C57BL/6 mice, Sprague-Dawley rats, New Zealand White rabbits, domestic cats, and beagles. Each component—including probe cable shielding, blanket insulation material, and control unit PCB layout—meets RoHS 2011/65/EU directives. While not certified as medical devices, the system is routinely deployed in GLP-regulated toxicology studies and FDA-submitted nonclinical pharmacology reports where temperature stability is a critical protocol parameter (e.g., ISO 10993-2, OECD 407, and USP guidance on animal model integrity). Documentation packages include factory calibration certificates traceable to NIST standards.

Software & Data Management

This analog-controlled system operates independently of host computers and does not require proprietary software drivers or USB interfaces. Temperature data output is available via analog voltage (0–10 V DC, linearly scaled to 35–40 °C) on a dedicated BNC port—enabling direct integration into existing data acquisition frameworks (e.g., LabChart, Spike2, or custom Python-based acquisition scripts using National Instruments DAQmx). All units ship with full technical documentation, including schematic diagrams, calibration procedures, and electrical safety test reports. Audit trails are maintained manually per GLP requirement; no electronic record archiving or 21 CFR Part 11 functionality is provided, consistent with its classification as ancillary hardware rather than regulated clinical instrumentation.

Applications

• Intraoperative thermoregulation during stereotaxic surgery, craniotomy, or spinal cord injury models.
• Maintenance of core temperature during long-duration electrophysiology experiments (e.g., in vivo single-unit recordings, field potential mapping).
• Supporting metabolic studies requiring stable baseline physiology (e.g., indirect calorimetry, microdialysis perfusion protocols).
• Peri-anesthetic monitoring in rodent and companion animal anesthesia research aligned with AVMA guidelines.
• Use in combination with laser Doppler flowmetry, thermal imaging, or infrared thermography setups where electromagnetic compatibility is essential.

FAQ

Can this system be used with MRI-compatible setups?
No—the blanket contains conductive heating elements and metallic probe housings; it is not MRI-safe and must be removed prior to magnetic resonance imaging.
Is the flexible probe suitable for neonatal mice or rat pups?
The 2 mm diameter flexible probe is not recommended for animals under 10 g; alternative thermocouple-based solutions with sub-millimeter probes are advised for neonatal applications.
Does the controller support remote temperature setpoint adjustment via TTL or analog input?
No—setpoint adjustment is exclusively manual via front-panel rotary encoder; no external control interface is provided.
What is the maximum continuous operating time at 40 °C ambient?
The system is rated for indefinite operation under standard laboratory conditions (20–25 °C ambient); thermal derating is not required below 35 °C blanket surface temperature.
Are replacement probes and blankets available as standalone components?
Yes—Harvard Apparatus supplies OEM-grade replacement probes (flexible P/N: 72-10100, rigid P/N: 72-10200) and blankets (P/Ns: 72-10300, 72-10400, 72-10500) with full traceability and batch-specific calibration data.