Official Achievement Announcement

By deeply integrating materials science and surface engineering, we have launched the Haokai Series distal housings, specifically engineered to withstand complex biochemical environments inside the human body and stringent sterilization challenges. Manufactured from medically certified 316L stainless steel, titanium alloy (Ti‑6Al‑4V) and emerging cobalt‑chromium alloys, the series features our patented Gradient Functionalized Surface Treatment (GFST) technology, which builds a multi‑layer protection and functional system from nanoscale to microscale on component surfaces. Demonstrating outstanding performance in accelerated corrosion tests, cytotoxicity tests and long‑term fatigue tests, the product ensures core structural components of endoscopes remain biosafe and mechanically reliable over hundreds of thousands of service cycles.

R&D Background & Pain Points

As the outermost component of endoscopes that directly contacts human tissues and body fluids, distal housings rely heavily on material and surface properties to guarantee device safety and service life. Multiple clinical challenges exist. First, body fluids are natural electrolytes. After long‑term repeated sterilization (high‑temperature high‑pressure sterilization, chemical immersion) and exposure to blood and digestive fluids, stainless steel housings face risks of pitting corrosion, crevice corrosion and stress‑corrosion cracking, with corrosion products potentially triggering tissue inflammation or allergic reactions. Second, rough or chemically unstable surfaces tend to form biofilms, raising cross‑infection risks. Third, repeated bending and impact may create micro‑surface damage, initiating fatigue cracks. Conventional single‑step passivation or polishing treatments can no longer meet growing demands for safety and durability, making materials and surface finishing a bottleneck limiting reliability of high‑end endoscopes.

Core Technological Innovations

1. Deep Purification and Texture Control of Medical‑Grade MaterialsPartnering with top‑tier material suppliers, we conduct strict compositional analysis and microstructural inspection on incoming medical‑grade bar stock. For critical applications, further purification is achieved via vacuum consumable remelting and other processes, reducing impurity elements (e.g., S, P) to extremely low levels. Custom heat‑treatment regimes are implemented before and after machining to regulate grain size and precipitate phases, balancing excellent machinability with optimal corrosion resistance and fatigue strength. For instance, solution treatment plus low‑temperature aging is applied to 316L stainless steel to produce a homogeneous austenitic structure with fine carbide distribution.
2. Gradient Functionalized Surface Treatment (GFST) TechnologyOur core patented surface treatment technology consists of three gradient layers:
3. Substrate Reinforcement Layer: Low‑temperature plasma nitriding or carburizing forms a several‑micron‑thick diffusion layer on the component surface, raising surface hardness above HV 1000 to drastically improve wear and scratch resistance without compromising substrate toughness.
4. Corrosion‑Resistant Passivation Layer: Electrochemical anodization (for titanium alloys) or optimally formulated nitric acid passivation (for stainless steel) generates a dense, stable passivation film rich in chromium/titanium oxides. Controlled potential and electrolyte conditions produce thicker, more uniform films with enhanced self‑healing capacity.
5. Bio‑Functional Top Layer: Via chemical grafting or physical vapor deposition (PVD), an ultra‑hydrophilic coating or silver‑/copper‑doped diamond‑like carbon (DLC) antibacterial coating is introduced on the outermost surface. The ultra‑hydrophilic layer reduces protein and bacterial adhesion, while the antibacterial coating delivers contact‑based bacteriostatic effects.
6. Full‑Process Cleanliness and Contaminant ControlAll procedures from raw‑material cutting to final packaging are performed in Class 10 000 or higher‑cleanliness environments. A complete cleanliness verification workflow is established using particle counting, ion chromatography and total organic carbon analysis to ensure components meet specified cleanliness standards (e.g., particle count per square centimeter) prior to delivery, eliminating any contamination sources that may trigger biological reactions.

Working Mechanism

Protection offered by Haokai Series housings forms a multi‑level defense system combining active and passive mechanisms. At the intrinsic material level, high‑purity, well‑structured metal substrates provide the first line of defense against corrosion and fatigue. The gradient functionalized surface treatment constructs a robust artificial exoskeleton: the substrate reinforcement layer acts like armor, resisting friction and scratches as instruments navigate narrow lumens and preventing fresh reactive metal surfaces from forming; the corrosion‑resistant passivation layer functions as anti‑rust coating, with its dense oxide film isolating the substrate from electrochemical contact with corrosive media and rapidly self‑healing even minor damages under high‑chromium/titanium conditions; the bio‑functional top layer serves as both a non‑stick surface and antibacterial coating, lowering bio‑contamination risks via physical and chemical means. These three gradient‑transition layers bond firmly to prevent secondary hazards caused by coating delamination. Furthermore, ultra‑high surface smoothness (Ra ≤ 0.1 μm after electropolishing) inherently inhibits bacterial colonization and corrosion initiation.

Performance Validation

Material performance test results are exceptional. Potentiodynamic polarization tests per ASTM F2129 show that GFST‑treated 316L housings exhibit a pitting breakdown potential (Eb) over 300 mV higher and an order‑of‑magnitude lower corrosion current density compared with conventionally passivated samples. All biological evaluations per ISO 10993 (cytotoxicity, sensitization, irritation) are passed. Taber abrasion testing demonstrates 5‑fold higher wear resistance than polished‑only surfaces. In accelerated aging tests simulating the harshest clinical conditions (alternating cycles of 134 °C high‑temperature high‑pressure sterilization, 2% glutaraldehyde immersion and simulated body fluid exposure), samples show no visible corrosion pits, intact surface coatings and stable critical dimensions after cycles equivalent to 5 years of real‑world use. Long‑term monitoring data from multiple endoscope manufacturers confirms that products equipped with Haokai housings feature significantly lower failure rates caused by distal‑end corrosion or wear than the industry average.

R&D Strategy & Philosophy

Our strategy is to design reliability into every atom of materials and surfaces. We believe that for devices implanted or in long‑term contact with the human body, biocompatibility and durability are not post‑hoc add‑on properties, but core design objectives defined from the very start of material selection and manufacturing process development. We have built comprehensive databases for material‑surface performance and failure cases, conducting in‑depth research on long‑term behaviors of each material‑process combination under simulated environments.Our philosophy: Behind every real‑time light signal and every sharp image generated inside the patient's body lies uncompromising material science. More than component manufacturers, we are guardians of patient safety, transforming cold metals into intelligent structures that harmonize with human tissues and deliver long‑term service through our superior craftsmanship.

Future Outlook

Future biomaterial surfaces will become more intelligent and interactive. We are researching responsive coatings, such as pH‑responsive coatings that locally release antibacterial agents at infected sites with abnormal pH values, or temperature‑responsive coatings that adjust hydrophilicity/hydrophobicity at specific temperatures to control protein adsorption. Meanwhile, bioactive surfaces are being explored, where surface‑grafted biomolecules (e.g., RGD peptides) actively promote favorable healing with specific tissues and reduce fibrous capsule formation - a feature critical for long‑term indwelling monitoring endoscopes. In addition, we investigate applications of biodegradable metals (e.g., magnesium alloys, zinc alloys) in single‑use endoscope housings, striving to balance strength, machinability and controlled degradation rates to deliver new solutions for green healthcare.