心脏起搏器是怎么工作的？
How does a cardiac pacemaker work?
它通过电极感知心脏电活动，当节律过慢或停搏时，由脉冲发生器发出微小电脉冲刺激心肌收缩，维持正常心率。
Electrodes sense the heart's electrical activity, and when the rhythm is too slow the pulse generator sends tiny electrical pulses to make the muscle contract at a normal rate.
难度 专业 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
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出处备注：此条未指向带版次的可引用著作（通识性内容、机构文件或未展开的英文书名），本库不提供独立书目出处；如需精确引用，需由编辑补全具体篇目与版次。
Medtronic 心脏起搏器；ISO 13485 医疗器械
Medtronic cardiac pacemakers; ISO 13485 medical devices
#生物医学 #起搏器
肌电假肢为什么能听懂残肢肌肉的"电信号"？
How does a myoelectric prosthetic understand the electrical signals in a residual limb?
人想动手时，大脑的运动指令沿神经传到残肢残留的肌肉，肌肉收缩产生微弱的电信号（肌电，幅值约微伏级）。肌电假肢在残肢表面贴电极捕捉这些信号，经过放大、滤波后提取特征（如幅值和频谱模式），再用模式识别判断使用者的动作意图——是握拳、伸腕还是旋前。控制器再把意图映射为微型直流电机或伺服驱动的假手动作。因为信号来自使用者本人的神经肌肉系统，动作自然、无需切换开关；但肌电信号易受出汗和电极移位干扰，识别准确率仍是研究重点。
When you intend to move, motor commands travel down nerves to the muscles left in the residual limb, which contract and emit faint electrical signals (EMG, on the order of microvolts). A myoelectric prosthesis picks these up with surface electrodes, then amplifies, filters, and extracts features such as amplitude and spectral patterns, and uses pattern recognition to infer the intent — grasp, wrist extension, or pronation. A controller then maps that intent to micro DC motors or servos moving the hand. Because the signals come from the user's own neuromuscular system, the motion feels natural and needs no switch training; but EMG is disturbed by sweat and electrode shift, so recognition accuracy remains an active research focus.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Bronzino《生物医学工程手册》；医疗器械标准（ISO 13485）
Bronzino, Biomedical Engineering Handbook; medical device standards (ISO 13485)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL4781638W：The Biomedical Engineer
#肌电假肢 #EMG #模式识别
脑机接口怎么读取"想法"并把它变成控制指令？
How does a brain-computer interface read intentions and turn them into commands?
脑机接口（BCI）采集脑电信号并解码意图。非侵入式方案用头皮电极帽记录脑电图（EEG），信号弱、噪声大，主要利用事件相关电位（如P300）或运动想象时的感觉运动节律；侵入式方案把电极阵列植入皮层（如犹他阵列），直接记录神经元的锋电位，空间分辨率和信息量大得多，但需要开颅手术，还面临长期生物相容性风险。信号经预处理、特征提取后交给分类器（线性判别分析、支持向量机或深度学习）解码成动作意图，再映射到机械臂或光标。目前受限于信噪比、训练成本和长期稳定性，脑机接口仍主要处于科研与临床试验阶段。
A brain-computer interface (BCI) records brain signals and decodes intent. Non-invasive caps record EEG at the scalp — weak and noisy — relying on event-related potentials like P300 or sensorimotor rhythms during motor imagery; invasive implants such as the Utah array sit on the cortex and record spike trains with far higher spatial resolution and information, but require surgery and carry long-term biocompatibility risks. After preprocessing, feature extraction, and classifiers (LDA, SVMs, or deep networks), the signal is decoded into motor intents and mapped to a robot arm or cursor. Limited by signal-to-noise, training cost, and long-term stability, BCIs still live mainly in research and clinical trials.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Bronzino《生物医学工程手册》；医疗器械标准（ISO 13485）
Bronzino, Biomedical Engineering Handbook; medical device standards (ISO 13485)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL4781638W：The Biomedical Engineer
#脑机接口 #EEG #神经解码
MRI是怎么"看见"人体内部软组织的？
How does MRI see soft tissue inside the body?
MRI依赖氢核的核磁共振。人体含大量水，氢原子核（质子）自带自旋磁矩，在强磁场中沿磁场方向取向并绕其进动。射频脉冲以共振频率激发质子，使其相位一致并偏转；脉冲停止后质子弛豫回到平衡态并释放射频信号。不同组织的T1、T2弛豫时间不同，接收线圈测得信号后经傅里叶变换重建出图像。通过调整脉冲序列的加权（T1加权或T2加权）可以突出不同组织的对比，对脑、脊髓、关节等软组织分辨率极高，而且没有电离辐射。
MRI exploits nuclear magnetic resonance of hydrogen. The body is mostly water, and protons spin with a magnetic moment, aligning with and precessing about a strong field. A resonant RF pulse tips them into coherence and deflection; when the pulse stops, they relax back and emit RF signals. Tissues differ in T1 and T2 relaxation times, and receiver coils capture the signals for Fourier reconstruction into images. Weighting the pulse sequence (T1- or T2-weighted) emphasizes different contrast, giving superb soft-tissue detail in brain, spine, and joints with no ionizing radiation.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Kak & Slaney《CT 原理》；Haacke 等《MRI 原理》；超声成像（Hendee & Ritenour）
Kak & Slaney, Principles of Computerized Tomographic Imaging; Haacke et al., Magnetic Resonance Imaging; ultrasound (Hendee & Ritenour)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL4974986W：Principles of computeri
#核磁共振 #弛豫 #软组织成像
人工心脏瓣膜为什么必须能扛住每一次心跳的冲击？
Why must an artificial heart valve survive the slam of every heartbeat?
心脏瓣膜每天开关约十万次，主动脉瓣闭合瞬间要承受约120毫米汞柱的跨瓣压差和急速反向的血流冲击。人工瓣膜分机械瓣（热解碳双叶瓣）与生物瓣（猪或牛心包瓣）：机械瓣寿命长但需终身服用抗凝药，生物瓣血流更接近生理、可减少抗凝，但十年左右可能钙化退化。设计的关键在于低湍流、低剪切的血流动力学和极高的疲劳寿命。
A heart valve opens and closes about 100,000 times a day, and the aortic valve slams shut against a pressure difference of about 120 mmHg and fast reversing blood flow. Artificial valves come in two types: mechanical (bileaflet pyrolytic carbon) and biological (porcine or bovine pericardium). Mechanical valves last long but require lifelong anticoagulation; tissue valves flow more naturally with less anticoagulation but may calcify and fail within about a decade. The design challenges are low-turbulence, low-shear hemodynamics and enormous fatigue life.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Ratner、Hoffman、Schoen & Lemons，《生物材料科学：医用材料导论》（第3版）
Ratner, Hoffman, Schoen & Lemons, 'Biomaterials Science: An Introduction to Materials in Medicine' (3rd ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787302141884（豆瓣书目条目: 生物材料科学医用材料导论）
#人工心脏瓣膜 #疲劳寿命 #血流动力学
为什么做核磁共振检查前必须摘掉所有金属物品？
Why must you remove all metal objects before an MRI scan?
MRI机器内部是超导磁体产生的强磁场，场强通常是1.5特斯拉或3特斯拉，约为地磁的3万到6万倍。硬币、钥匙、轮椅等铁磁性物品会被瞬间吸向磁体，速度快到足以伤人损机；体内的金属植入物（如起搏器、人工关节、颅内动脉瘤夹）则可能被牵拉移动、发热或失效。所以受检者必须取下金属并接受安全检查，这是MRI的铁律。
Inside an MRI is a superconducting magnet producing typically 1.5 or 3 tesla — 30,000 to 60,000 times Earth's field. Ferromagnetic objects like coins, keys, wheelchairs, or steel-bearing tattoo inks get yanked toward the magnet fast enough to injure people and damage the machine; metal implants such as pacemakers, joint replacements, and aneurysm clips can be pulled, heated, or disabled. That is why patients must remove all metal and pass screening — it is an absolute rule of MRI.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Kak & Slaney《CT 原理》；Haacke 等《MRI 原理》；超声成像（Hendee & Ritenour）
Kak & Slaney, Principles of Computerized Tomographic Imaging; Haacke et al., Magnetic Resonance Imaging; ultrasound (Hendee & Ritenour)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL4974986W：Principles of computeri
#核磁共振 #磁场 #安全
CT是怎样"拍"出身体一层层切片的？
How does a CT scanner produce cross-sectional slices of the body?
CT用X射线管围绕人体旋转扫描，对面的探测器接收穿过身体后衰减的射线，从数百上千个角度采集投影数据。计算机用滤波反投影或迭代重建算法，从这些投影解算出每个体素的X射线衰减系数，重建出断层图像。不同组织因密度差异衰减不同：骨最亮、软组织居中、空气最暗。与普通X光片把前后组织叠成阴影不同，CT能分辨同一层面的空间关系。
A CT scanner spins an X-ray tube around the patient while detectors on the far side capture the attenuated beam, gathering projections from hundreds or thousands of angles. A computer reconstructs each voxel's X-ray attenuation coefficient from those projections using filtered back-projection or iterative reconstruction, producing tomographic slices. Tissues differ in attenuation by density: bone is brightest, soft tissue in between, and air darkest. Unlike a plain X-ray, which stacks tissues into overlapping shadows, CT resolves structures within a single slice.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Kak & Slaney《CT 原理》；Haacke 等《MRI 原理》；超声成像（Hendee & Ritenour）
Kak & Slaney, Principles of Computerized Tomographic Imaging; Haacke et al., Magnetic Resonance Imaging; ultrasound (Hendee & Ritenour)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL4974986W：Principles of computeri
#CT #断层重建 #X射线