Custom Brain Cooling Device

In 2018, the customer approached us with a concept for a medical device to cool the brain. It was aimed at treating and rehabilitating patients with strokes, traumatic brain injuries, neurological disorders, CNS diseases, and vascular cerebral dysfunctions. It also had applications in substance withdrawal management and psychiatric care for affective or psychotic episodes.

A joint effort from mechanical engineers, electronics developers, programmers, and manufacturing specialists resulted in a functional TRL-6 prototype (suitable for near-real conditions testing). It demonstrated the feasibility of the design, balancing performance with size constraints while lowering future production costs. This stage involved intensive medical device prototyping under clinical conditions.

Development of the Portable Cooling Unit

The first phase focused on reducing the prototype's size and weight by nearly half, without sacrificing cooling power. We worked within a strict cost limit, avoiding expensive miniature components. Our team developed an ergonomic design and built prototypes of key modules, including:

• The control system
• The compressor block with valve system
• Structural enclosure components

The control system and valve-integrated compressor block required a complete redesign, departing from the principles established in the customer’s earlier scientific model. For example, the addition of a thermostatic valve necessitated tuning impulse oscillations to reach low temperatures quickly and stabilize them.

The enclosure was designed as a vertical cuboid, featuring:

• A touchscreen interface
• A quick-release helmet connector
• A coolant container

All major components were tested individually before being integrated into the TRL-6 prototype.

The prototype was refined to stabilize the cooling process and user interface. It successfully passed clinical trials, including during the COVID-19 pandemic, when demand for temperature regulation equipment surged.

Thanks to integrated handles and a helmet stand, the system was highly mobile. This version included a single cooling circuit, measured approximately 480 × 310 × 450 mm, and weighed 23 kg without refrigerant.

Scaling Up: From Single- to Dual-Circuit System

After receiving clinical feedback, we began upgrading the system. The original version couldn’t cool multiple body zones simultaneously, limiting its therapeutic versatility. Also, the single-channel setup wasn’t optimal for high-throughput medical facilities.

Testing confirmed the feasibility of a dual-channel system that could:

• Cool different parts of one patient’s body
• Serve two patients at once, each with individual temperature control

We began developing a dual-circuit version. 

The first iteration used a single compressor supplying refrigerant to two parallel freon circuits with valve-based flow regulation. However, the refrigerant favored one circuit, and the compressor couldn’t consistently reach target temperatures.

We then fully redesigned the architecture and introduced propylene glycol as a secondary coolant. Here's how the new system works:

• The compressor cools freon, which then chills the circulating propylene glycol.
• The glycol circulates through the helmets, maintaining contact-surface temperatures as low as 3°C and ensuring even cooling thanks to its high heat capacity.

Four PID-controlled pumps dynamically regulate flow based on sensor data. The system delivers no less than 80 W of cooling power per channel, achieving a brain cortex cooling rate of 1.0–1.5°C per hour during the initial 2–3 hours of therapy.

The device operates continuously for up to 48 hours and maintains freon temperatures in the primary circuit from –10°C to +20°C.

Helmet Development

The customer also tasked us with designing a new universal helmet to enhance patient comfort while delivering consistent cooling. The main challenge was ensuring a snug fit across a wide range of head sizes.

We opted for a medical-grade silicone helmet rather than one with mechanical adjusters, which would have significantly increased production costs.

To ensure effective cooling and a reliable fit, we began by analyzing anthropometric data to define a universal helmet size that would accommodate a wide range of head shapes. This allowed us to simulate the layout of internal coolant channels with the goal of maximizing heat transfer and achieving uniform cooling across the scalp. During this phase, we also took into account the manufacturing limitations that affect the direction and geometry of the channels. Recognizing the importance of consistent contact between the helmet and the patient’s head, we performed deformation modeling to understand how the channels would behave when the helmet was worn. This led us to develop a custom internal channel design tailored to real-world conditions.

Before advancing to full-scale prototyping, we conducted a series of manufacturing trials to validate the feasibility of the proposed design. We produced test segments of the channels using custom-fabricated molds, allowing us to evaluate the structural integrity of the joints and the flexibility of the material under pressure, stretching, and bending. These trials confirmed that our manufacturing approach would be viable and allowed us to mitigate key technical risks before committing to full production.

There are currently no reliable solutions on the market for manufacturing a helmet of this type. In addition to developing a functional and hermetically sealed design, we also helped the customer reduce production costs by revising the manufacturing approach. Instead of relying on a more complex and expensive five-axis CNC process, we proposed the use of a simpler three-axis machine. Furthermore, we redesigned the helmet's construction to use four smaller components instead of two larger ones, making the system easier to assemble and more scalable for small-batch production.