Northwestern University in the United States: Research on small implantable temperature sensors for long-term monitoring of chronic intestinal inflammation
Crohn's disease is an inflammatory bowel disease (IBD) that can cause chronic inflammation of the digestive tract. Its specific symptoms and severity vary from person to person, including abdominal pain and spasms, chronic diarrhea, weight loss, and malnutrition. Importantly, Crohn's disease, as a chronic disease, has unpredictable characteristics and may go through both attack and remission phases, requiring long-term management by patients.However, due to the inability of existing diagnostic tools such as endoscopy and biopsy to capture sudden acute attacks of enteritis, monitoring Crohn's disease faces challenges, resulting in approximately 70% of Crohn's disease patients having to undergo intestinal resection surgery.
Based on this, Professor John A. Rogers from Northwestern University in the United States developed a wireless miniature implantable temperature sensor for real-time and long-term monitoring of chronic inflammation in the intestine. The sensor is small in size and light in weight, and can be comfortably implanted into the abdominal cavity of mice and fixed on muscle tissue. It also uses Bluetooth low-power technology to communicate with external devices and can achieve long-term testing for 4 months.
The gut is a dynamic, fragile organ, especially in patients with Crohn's disease, where damaged tissue is more vulnerable. Traditional plug-in or external sensors are difficult to work stably in the gut over a long period of time. The work used a mouse model with a custom-designed sensor that was small (12.8 × 8.2 × 5.8 mm3), lightweight (~0.58 g), and had a smooth surface profile (roughness Sa = 2.8 ± 1.6 μm), a very small proportion of the mouse volume.The small size, smooth surface, and biocompatible packaging material of the sensor can reduce friction and irritation with intestinal tissue, ensure long-term stable operation, and avoid additional damage to the intestine. And the intestine is a hollow organ, which requires high positioning and accuracy of sensors in different parts.The system integrates low-power Bluetooth chips (BLE SoC) and temperature sensors (resolution~0.01 ° C), powered by button batteries (with a battery life of approximately 10.7 weeks). The sensor is designed to be fixed on the abdominal muscles and in direct contact with the intestine to detect temperature. The stable fixed position and high-precision sensors ensure accurate measurement of intestinal temperature fluctuations.
This study used the established Crohn's disease like colitis mouse model (SAMP1/YitFc strain) for experimentation, with their parent strain (AKR/J; disease-free, colitis free) as the control. As shown in Figure 2. The sensor can effectively capture the temperature fluctuations in the intestinal tract of experimental group mice and discover obvious super diurnal rhythms. These fluctuation characteristics appear at frequencies of f=2, 3, and 4, which are related to inflammatory cytokines and stress hormones (such as TNF) in the blood α、 IL-1 β Related to the concentration changes of ACTH.Experiments have shown that temperature fluctuations caused by inflammatory activity can serve as an effective warning signal, providing important information about disease activity and progression, and helping doctors identify early symptoms of Crohn's disease. In contrast, the intestinal temperature fluctuations of the control group mice did not exhibit similar ultra diurnal rhythm characteristics, indicating that this monitoring method can distinguish between diseased and healthy individuals.Secondly, the temperature monitoring of the sensor shows that early signs of inflammatory activity can be identified approximately five weeks before the appearance of visible lesions, providing a valuable time window for early intervention and treatment of Crohn's disease. The experiment also found that as the disease progresses and age increases, the average temperature of the intestine shows a significant long-term downward trend, reflecting that inflammation and tissue damage gradually worsen over time. This is consistent with the results of microstructural examination, showing a gradual expansion of the inflammatory lesion and an increase in the accumulation of inflammatory cytokines and immune cells.
The experimental results also revealed a receptor with anti-inflammatory effects (PPAR) γ） The phenomenon of gradually decreasing expression in inflammatory activity. In the fluctuation of intestinal temperature in experimental mice, PPAR γ The positive cells at the temperature trough are significantly lower than the peak, and the overall expression level decreases with the progression of inflammation. This indicates that PPAR γ It may be related to the regulation of inflammation and immune response, reflecting the complexity and systemic nature of intestinal inflammatory activity.
Source: Sensor Expert Network