# Quantum Biomedical Sensing — From Anatomy to Field Dynamics

## SOTA Research Document — RF Topological Sensing Series (12/12)

**Date**: 2026-03-08
**Domain**: Quantum Biomedical Sensing × Graph Diagnostics × Ambient Health Monitoring
**Status**: Research Survey

---

## 1. Introduction

Medicine has historically been built on imaging anatomy: X-rays show bone density, MRI
reveals tissue structure, ultrasound maps organ geometry. But the body is not just anatomy.
Every organ, nerve, and cell generates electromagnetic fields as a byproduct of function.
The heart's electrical cycle produces magnetic fields detectable meters away. Neurons fire
in femtotesla-scale magnetic fluctuations. Blood flow carries ionic currents that create
measurable magnetic disturbances.

Quantum sensors — operating at picotesla and femtotesla sensitivity — can observe these
fields directly. Combined with graph-based topological analysis (minimum cut, coherence
detection, RuVector temporal tracking), this creates a fundamentally new diagnostic paradigm:

**Monitoring the electromagnetic physics of life in real time.**

This document explores seven biomedical sensing directions, their integration with the RF
topological sensing architecture, and the path from research concept to clinical reality.

---

## 2. Whole Body Biomagnetic Mapping

### 2.1 Organ-Level Electromagnetic Fields

Every organ generates structured electromagnetic signals:

```
Biomagnetic Field Strengths:

    Source              | Magnetic Field  | Frequency    | Classical Detection
    ─────────────────────────────────────────────────────────────────────────
    Heart (MCG)         | 10-100 pT       | 0.1-40 Hz    | SQUID (clinical)
    Brain (MEG)         | 0.01-1 pT       | 1-100 Hz     | SQUID (research)
    Skeletal muscle     | 1-10 pT         | 20-500 Hz    | SQUID (research)
    Peripheral nerve    | 0.01-0.1 pT     | 100-10k Hz   | Not yet practical
    Fetal heart         | 1-10 pT         | 0.5-40 Hz    | SQUID (clinical)
    Eye (retina)        | 0.1-1 pT        | DC-30 Hz     | Research only
    Stomach             | 1-5 pT          | 0.05-0.15 Hz | Research only
    Lung (deoxy-Hb)     | ~0.1 pT         | 0.1-0.3 Hz   | Not yet practical

    Quantum sensor thresholds:
    NV Diamond:  ~1 pT/√Hz  → Heart, muscle, stomach
    SERF:        ~0.16 fT/√Hz → All above including brain
    SQUID:       ~1 fT/√Hz  → All above
```

### 2.2 Biomagnetic Topology Map

Instead of measuring single channels (like ECG leads), a dense quantum sensor array builds
a continuous electromagnetic topology map:

```
Dense Biomagnetic Array (conceptual):

    ┌────────────────────────────────────┐
    │  Q   Q   Q   Q   Q   Q   Q   Q    │
    │                                     │
    │  Q   ┌─────────────────┐   Q   Q   │    Q = Quantum sensor
    │      │                 │            │
    │  Q   │     Subject     │   Q   Q   │    128-256 sensors
    │      │     (supine)    │            │    ~5 cm spacing
    │  Q   │                 │   Q   Q   │
    │      └─────────────────┘            │    Measures:
    │  Q   Q   Q   Q   Q   Q   Q   Q    │    - B-field vector (3 axes)
    │                                     │    - At each sensor position
    │  Q   Q   Q   Q   Q   Q   Q   Q    │    - Continuously at 1 kHz
    └────────────────────────────────────┘

    Output: B(x, y, z, t) — 4D biomagnetic field map
```

### 2.3 Graph-Based Biomagnetic Analysis

The sensor array naturally forms a graph:

```
Biomagnetic Sensing Graph:

    Nodes: V = {sensor positions}  (128-256)
    Edges: E = {sensor pairs}
    Weights: w_ij = coherence(B_i(t), B_j(t))

    Coherence metric:
    C_ij = |⟨B_i(t) × B_j*(t)⟩| / √(⟨|B_i|²⟩ × ⟨|B_j|²⟩)

    High coherence → sensors measuring same source
    Low coherence  → sensors in different field regions

    Minimum cut reveals:
    - Boundaries between different organ field patterns
    - Regions where field topology changes (abnormalities)
    - Dynamic boundaries that shift with cardiac/respiratory cycle
```

### 2.4 Clinical Applications

| Application | Field Strength | Sensors Needed | Resolution | Timeline |
|-------------|---------------|----------------|------------|----------|
| Cardiac mapping (MCG) | 10-100 pT | 36-64 | ~2 cm | Available |
| Fetal monitoring | 1-10 pT | 36 | ~3 cm | 2027 |
| Muscle disorder diagnosis | 1-10 pT | 64 | ~1 cm | 2028 |
| Peripheral neuropathy | 0.01-0.1 pT | 128 | ~5 mm | 2030 |
| Full body mapping | 0.01-100 pT | 256 | ~2 cm | 2032 |

---

## 3. Neural Field Imaging Without Electrodes

### 3.1 Brain Magnetometry

Brain activity generates femtotesla-scale magnetic fields from ionic currents in neural tissue:

```
Neural Field Generation:

    Dendrite      Axon
    ─┬─┬─┬─    ────────→
     │ │ │       Action potential
     ↓ ↓ ↓       ~100 mV, ~1 ms
    Synaptic
    currents     Primary current: intracellular
    (~1 nA)      Volume current: extracellular return

    Magnetic field at scalp from ~50,000 synchronous neurons:
    B ≈ µ₀ × N × I × d / (4π × r²)
    B ≈ 4πe-7 × 5e4 × 1e-9 × 0.02 / (4π × 0.04²)
    B ≈ 100 fT

    Required sensitivity: < 10 fT/√Hz
    NV diamond (current): ~1 pT/√Hz — not yet sufficient
    NV diamond (projected 2028): ~10 fT/√Hz — approaching
    SERF magnetometer: ~0.16 fT/√Hz — sufficient now
    OPM (optically pumped): ~5 fT/√Hz — sufficient now
```

### 3.2 Wearable MEG with Quantum Sensors

Traditional MEG uses 300+ SQUID sensors in a rigid cryogenic helmet. Quantum alternatives:

```
Traditional MEG:                    Quantum MEG:
┌──────────────────┐               ┌──────────────────┐
│  ┌──────────┐    │               │                  │
│  │ Cryostat │    │               │  OPM sensors     │
│  │ (4K, LHe)│    │               │  mounted on      │
│  │          │    │               │  flexible cap    │
│  │  SQUIDs  │    │               │                  │
│  │  306 ch  │    │               │  64-128 sensors  │
│  └──────────┘    │               │  ~5 fT/√Hz each  │
│                  │               │  Room temperature │
│  Fixed position  │               │  Head-conforming  │
│  2-3 cm gap      │               │  <1 cm gap        │
│  $2-3M system    │               │  ~$200K system    │
│  Immobile patient│               │  Patient moves    │
└──────────────────┘               └──────────────────┘

Signal improvement from closer sensors:
    B ∝ 1/r² → 50% closer → 4× signal
    Plus conformal fit → better source localization
```

### 3.3 Neural Coherence Graph Analysis

```
Neural Coherence Sensing Graph:

    Nodes: V = {MEG sensor positions}
    Edges: E = {all sensor pairs within 10 cm}
    Weights: w_ij = spectral_coherence(B_i, B_j, f_band)

    Frequency bands:
    δ (1-4 Hz):   Deep sleep, pathology
    θ (4-8 Hz):   Memory, navigation
    α (8-13 Hz):  Relaxation, attention
    β (13-30 Hz): Motor planning, cognition
    γ (30-100 Hz): Binding, consciousness

    Per-band coherence graph → per-band minimum cut

    Healthy brain: High coherence within functional networks
                   Clear cuts between networks

    Seizure onset: Coherence boundaries shift
                   Cut value drops (hypersynchrony spreads)

    Anesthesia depth: Progressive loss of long-range coherence
                      Cuts fragment into many small partitions
```

### 3.4 Applications

| Application | What Mincut Reveals | Clinical Value |
|-------------|-------------------|----------------|
| Seizure detection | Expanding hypersynchronous region | Early warning (seconds before clinical) |
| Anesthesia monitoring | Fragmentation of coherence | Prevent awareness during surgery |
| Dementia screening | Loss of long-range coherence | Early Alzheimer's biomarker |
| Depression monitoring | Altered frontal-parietal cuts | Treatment response tracking |
| BCI input | Motor cortex coherence patterns | Non-invasive neural decode |
| Concussion assessment | Altered connectivity boundaries | Objective severity measure |

---

## 4. Ultra-Sensitive Circulation Sensing

### 4.1 Hemodynamic Magnetic Signatures

Blood is a moving ionic fluid that generates measurable magnetic fields:

```
Blood Flow Magnetism:

    Ionic composition:
    Na⁺: 140 mM, K⁺: 4 mM, Ca²⁺: 2.5 mM, Cl⁻: 100 mM

    Flow velocity in aorta: ~1 m/s
    Cross-section: ~5 cm²

    Magnetic field from flow (simplified):
    B ≈ µ₀ × σ × v × d / 2
    where σ = blood conductivity ≈ 0.7 S/m

    B ≈ 4πe-7 × 0.7 × 1 × 0.025 / 2
    B ≈ 11 nT (at vessel wall)
    B ≈ 1-10 pT (at body surface, after 1/r² decay)

    Detectable with: NV diamond, SERF, SQUID

    Capillary flow (v ~ 1 mm/s, d ~ 10 µm):
    B_surface ≈ 0.01-0.1 fT
    Detectable with: SERF, SQUID (with averaging)
```

### 4.2 Vascular Topology Graph

```
Vascular Sensing Architecture:

    Sensor array over limb/organ:
    ┌────────────────────────┐
    │  Q   Q   Q   Q   Q    │
    │  Q   Q   Q   Q   Q    │   20 sensors over forearm
    │  Q   Q   Q   Q   Q    │   5 mm spacing
    │  Q   Q   Q   Q   Q    │
    └────────────────────────┘

    Graph construction:
    - Nodes: sensor positions
    - Edge weight: correlation of pulsatile flow signals
    - High correlation → sensors over same vessel branch
    - Low correlation → different vascular territories

    Minimum cut:
    - Separates vascular territories
    - Detects stenosis (abnormal flow boundary)
    - Maps collateral circulation

    Temporal evolution:
    - Graph changes with blood pressure cycle
    - Persistent changes → vascular disease
    - Acute changes → thrombosis, embolism
```

### 4.3 Clinical Applications

| Condition | Detection Method | Sensitivity | Current Gold Standard |
|-----------|-----------------|-------------|----------------------|
| Peripheral artery disease | Reduced pulsatile coherence | 80% stenosis | Doppler ultrasound |
| Deep vein thrombosis | Flow interruption boundary | ~5 mm clot | Compression ultrasound |
| Microvascular disease | Loss of capillary coherence | Sub-mm | Capillaroscopy |
| Stroke risk (carotid) | Turbulent flow signature | ~30% stenosis | CT angiography |

---

## 5. Cellular-Level Electromagnetic Signaling

### 5.1 Bioelectric Cell Communication

Emerging research suggests cells communicate through electromagnetic oscillations:

```
Cellular EM Signaling (Theoretical):

    Microtubule oscillations: ~1-100 MHz
    Membrane potential waves: ~0.1-10 Hz
    Mitochondrial EM emission: ~1-10 MHz
    Ion channel coherent fluctuations: ~1 kHz-1 MHz

    Field strengths at cell surface: ~1-100 µV/m
    Field at tissue surface: ~0.01-1 fT (extremely weak)

    Detection requires:
    - SERF magnetometers with fT sensitivity
    - Extensive averaging (minutes to hours)
    - Shielded environment (< 1 nT ambient)
    - Population-level coherence (millions of cells)
```

### 5.2 Inflammation and Immune Response

```
Inflammation Electromagnetic Signature:

    Healthy tissue:
    - Cells maintain coordinated membrane potentials
    - Coherent EM emission within tissue volume
    - Graph edge weights high (intra-tissue coherence)

    Inflamed tissue:
    - Disrupted membrane potentials
    - Increased ionic flow (edema)
    - Changed tissue conductivity
    - Altered EM coherence patterns

    Detection via biomagnetic graph:
    - Inflammation region → drop in local coherence
    - Minimum cut isolates inflamed volume
    - Temporal tracking → inflammation progression

    Challenge: Extremely subtle signals
    Current TRL: 2 (laboratory concept)
    Practical timeline: 2035+
```

### 5.3 Tissue Repair Monitoring

Wound healing and tissue repair involve coordinated bioelectric signaling:

```
Tissue Repair Bioelectric Phases:

    Phase 1: Injury current (µA/cm²)
    → Measurable at ~1-10 pT at surface
    → Drives cell migration toward wound

    Phase 2: Proliferation signaling
    → Coordinated membrane depolarization
    → Coherent EM emission from healing zone

    Phase 3: Remodeling
    → Gradual restoration of normal patterns
    → Coherence approaches baseline

    Graph-based monitoring:
    - Track coherence recovery over days/weeks
    - Cut boundary shrinks as healing progresses
    - Stalled healing → persistent abnormal boundary
```

---

## 6. Non-Contact Diagnostics

### 6.1 Through-Air Vital Signs Detection

With sufficient sensitivity, quantum sensors detect vital signs without contact:

```
Non-Contact Detection Ranges:

    Signal          | At Body | At 1m  | At 3m  | Sensor Needed
    ────────────────────────────────────────────────────────────
    Heart (magnetic) | 100 pT  | 1 pT   | 0.01 pT | NV (1m), SERF (3m)
    Heart (electric) | 1 mV/m  | 10 µV/m | 1 µV/m  | Rydberg (all)
    Breathing (motion)| — via RF disturbance — | ESP32 mesh
    Muscle tremor    | 10 pT   | 0.1 pT | —       | NV (1m)
    Neural (MEG)     | 1 pT    | 0.01 pT| —       | SERF (1m only)

    Practical non-contact vital signs at 1-3m:
    ✅ Heart rate (magnetic + RF)
    ✅ Breathing rate (RF disturbance)
    ✅ Gross movement (RF + magnetic)
    ⚠️ Heart rhythm detail (1m only, quantum required)
    ❌ Neural activity (too weak beyond 1m)
```

### 6.2 Ambient Room Monitoring Architecture

```
Room-Scale Health Monitoring:

    ┌─────────────────────────────────────┐
    │                                     │
    │  E────E────E────E────E────E         │  E = ESP32 (RF sensing)
    │  │                        │         │  Q = Quantum sensor
    │  E    ┌──────────┐       E         │
    │  │    │          │       │         │  Layer 1: ESP32 RF mesh
    │  E    │  Person   │   Q  E         │  - Presence detection
    │  │    │  (bed)    │       │         │  - Movement tracking
    │  E    │          │       E         │  - Breathing (gross)
    │  │    └──────────┘       │         │
    │  E         Q             E         │  Layer 2: Quantum sensors
    │  │                        │         │  - Heart rhythm
    │  E────E────E────E────E────E         │  - Breathing (fine)
    │                                     │  - Muscle activity
    └─────────────────────────────────────┘

    Graph fusion:
    G_room = G_rf ∪ G_quantum

    RF edges: movement, presence, gross vitals
    Quantum edges: cardiac, respiratory, neuromuscular

    Combined mincut: Multi-scale boundary detection
    - Room-scale (person location) via RF
    - Body-scale (vital sign regions) via quantum
    - Organ-scale (cardiac boundaries) via quantum
```

### 6.3 Privacy-Preserving Design

Non-contact sensing raises privacy concerns. Architectural safeguards:

```
Privacy Architecture:

    Sensing Layer:
    - Raw data never stored (streaming processing)
    - No imaging (no cameras, no reconstructed images)
    - Only graph features extracted (coherence, cuts)

    Analysis Layer:
    - Outputs: {heart_rate, breathing_rate, movement_class}
    - No body shape, appearance, or identity information
    - Edge weights are anonymous (no biometric encoding)

    Alert Layer:
    - Only triggers on anomalies (fall, cardiac event)
    - Configurable sensitivity thresholds
    - Local processing (no cloud dependency)

    Key property: RF topology sensing is inherently
    privacy-preserving because it detects boundaries,
    not reconstructs images.
```

---

## 7. Coherence-Based Diagnostics

### 7.1 Physiological Synchronization

Health depends on coordinated regulation across multiple organ systems:

```
Physiological Coherence Networks:

    Cardiac ←→ Respiratory (RSA: respiratory sinus arrhythmia)
    Cardiac ←→ Autonomic (HRV: heart rate variability)
    Neural  ←→ Muscular   (motor coordination)
    Endocrine ←→ Metabolic (glucose regulation)
    Circadian ←→ All       (sleep-wake coordination)

    Each pair has measurable EM coherence:
    - Heart-lung coupling: detectable at 10 pT
    - Brain-muscle coupling: detectable at 1 pT
    - Autonomic coherence: via HRV spectral analysis
```

### 7.2 Disease as Coherence Breakdown

```
Coherence-Based Disease Model:

    Healthy state:
    ┌─────────────────────────────┐
    │  High coherence throughout   │
    │  Graph well-connected        │
    │  Min-cut value: HIGH         │
    │  Few distinct partitions     │
    └─────────────────────────────┘

    Early disease:
    ┌─────────────────────────────┐
    │  Local coherence drops       │
    │  Some edges weaken           │
    │  Min-cut value: DECREASING   │
    │  Emerging partition boundaries│
    └─────────────────────────────┘

    Advanced disease:
    ┌─────────────────────────────┐
    │  Widespread decoherence      │
    │  Multiple weak regions       │
    │  Min-cut value: LOW          │
    │  Multiple disconnected parts │
    └─────────────────────────────┘

    RuVector tracking:
    - Store coherence graph evolution over days/months
    - Detect gradual degradation trends
    - Alert on sudden coherence changes
    - Compare to population baselines
```

### 7.3 Graph Diagnostic Framework

```rust
/// Coherence-based diagnostic graph
pub struct PhysiologicalGraph {
    /// Sensor nodes (quantum + RF)
    nodes: Vec<SensorNode>,
    /// Coherence edges between sensors
    edges: Vec<CoherenceEdge>,
    /// Organ-system labels for graph regions
    regions: HashMap<OrganSystem, Vec<NodeId>>,
}

pub struct CoherenceEdge {
    pub source: NodeId,
    pub target: NodeId,
    pub coherence: f64,          // 0.0 to 1.0
    pub frequency_band: FreqBand, // Which physiological rhythm
    pub confidence: f64,
}

pub enum OrganSystem {
    Cardiac,
    Respiratory,
    Neural,
    Muscular,
    Vascular,
    Autonomic,
}

/// Diagnostic output from graph analysis
pub struct DiagnosticReport {
    /// Overall coherence score (0-100)
    pub coherence_index: f64,
    /// Per-system coherence
    pub system_scores: HashMap<OrganSystem, f64>,
    /// Detected boundaries (abnormal partitions)
    pub anomalous_cuts: Vec<CutBoundary>,
    /// Temporal trend
    pub trend: CoherenceTrend, // Improving, Stable, Degrading
    /// Comparison to baseline
    pub deviation_from_baseline: f64,
}
```

### 7.4 Specific Diagnostic Applications

| Condition | Coherence Signature | Detection Mechanism |
|-----------|-------------------|---------------------|
| Atrial fibrillation | Cardiac-respiratory desynchronization | RSA coherence drop |
| Heart failure | Multi-system decoherence | Global mincut decrease |
| Parkinson's disease | Motor-neural coherence oscillation | Tremor frequency peak in β-band |
| Sleep apnea | Respiratory-cardiac periodic drops | Cyclic coherence boundary shifts |
| Sepsis | Rapid multi-system decoherence | Fiedler value collapse |
| Diabetic neuropathy | Peripheral-central coherence loss | Progressive cut boundary expansion |
| Chronic fatigue | Subtle autonomic decoherence | Low HRV, altered cut dynamics |

---

## 8. Neural Interface Sensing

### 8.1 Passive Neural Readout

```
Non-Invasive Neural Interface:

    Traditional BCI:                    Quantum BCI:
    ┌──────────────┐                   ┌──────────────┐
    │ EEG electrodes│                   │ OPM array    │
    │ on scalp      │                   │ on scalp     │
    │               │                   │              │
    │ 10-20 µV      │                   │ 10-100 fT    │
    │ ~3 cm res     │                   │ ~5 mm res    │
    │ Contact gel   │                   │ No contact   │
    │ 256 channels  │                   │ 128 channels │
    └──────────────┘                   └──────────────┘

    Advantages of quantum MEG for BCI:
    - 10× better spatial resolution
    - No skin preparation or gel
    - Measures magnetic (volume conductor neutral)
    - Better deep source sensitivity
    - Compatible with movement
```

### 8.2 Motor Decode Without Implants

```
Motor Cortex Coherence Graph for BCI:

    128 OPM sensors over motor cortex
    → Coherence graph in β/γ bands (13-100 Hz)

    Motor planning state:
    - Pre-movement: coherence increases in motor strip
    - Lateralized: left vs right hand planning
    - Graded: force intention correlates with coherence magnitude

    Graph-based decode:
    - Compute per-band coherence graph
    - Track mincut partition changes
    - Partition shift LEFT → right hand intent
    - Partition shift RIGHT → left hand intent
    - Cut value magnitude → force/speed intention

    Accuracy estimates:
    - Binary (left/right): ~85-90% (matching invasive BCI)
    - Multi-class (5 gestures): ~60-70%
    - Continuous cursor control: comparable to EEG-based BCI
```

### 8.3 Adaptive Stimulation Feedback

For therapies using brain stimulation (TMS, tDCS):

```
Closed-Loop Stimulation with Quantum Sensing:

    ┌─────────┐     ┌──────────┐     ┌──────────┐
    │ Quantum │────→│ Coherence│────→│ Stimulate│
    │ Sensors │     │ Analysis │     │ Decision │
    └─────────┘     └──────────┘     └────┬─────┘
         ↑                                 │
         │          ┌──────────┐           │
         └──────────│  TMS/tDCS│←──────────┘
                    │  Actuator│
                    └──────────┘

    Feedback loop:
    1. Measure neural coherence graph
    2. Compute deviation from target pattern
    3. Adjust stimulation parameters
    4. Observe coherence response
    5. Iterate at 10-100 Hz

    Applications:
    - Depression treatment (restore frontal coherence)
    - Epilepsy suppression (detect and disrupt seizure spread)
    - Stroke rehabilitation (promote motor cortex reorganization)
    - Pain management (modulate somatosensory coherence)
```

---

## 9. Multimodal Physiological Observatory

### 9.1 Sensor Fusion Architecture

```
Multimodal Sensing Stack:

    Layer 4: Quantum Magnetic (fT-pT)
    ┌────────────────────────────────┐
    │  NV/OPM/SERF sensors           │   Cardiac, neural, muscular
    │  4-128 sensors per room        │   fields directly
    └────────────────┬───────────────┘
                     │
    Layer 3: RF Topological (CSI coherence)
    ┌────────────────┴───────────────┐
    │  ESP32 WiFi mesh               │   Movement, presence,
    │  16 nodes, 120 edges           │   breathing, gestures
    └────────────────┬───────────────┘
                     │
    Layer 2: Acoustic (optional)
    ┌────────────────┴───────────────┐
    │  Microphone array              │   Breathing sounds, heart
    │  8-16 MEMS mics                │   sounds, voice analysis
    └────────────────┬───────────────┘
                     │
    Layer 1: Environmental
    ┌────────────────┴───────────────┐
    │  Temperature, humidity,        │   Context for
    │  light, air quality            │   signal calibration
    └────────────────────────────────┘
```

### 9.2 Cross-Modal Coherence

```
Cross-Modal Graph Construction:

    G_multimodal = (V, E_rf ∪ E_quantum ∪ E_cross)

    E_rf: ESP32-to-ESP32 CSI coherence
    E_quantum: Quantum sensor-to-sensor B-field coherence
    E_cross: Cross-modal edges

    Cross-modal edge weight:
    w_cross(rf_i, quantum_j) = correlation(
        rf_coherence_change(t),
        magnetic_field_change(t)
    )

    High cross-modal coherence:
    → RF disturbance AND magnetic change co-located
    → Strong evidence of physical event

    Low cross-modal coherence:
    → RF change without magnetic change
    → Could be environmental (door, furniture)
    → Or magnetic change without RF change
    → Could be internal physiological event

    Minimum cut on multimodal graph:
    → Separates physical events from physiological events
    → Enables disambiguation impossible with single modality
```

### 9.3 Temporal Multi-Scale Analysis

```
Time Scales in Multimodal Sensing:

    Scale          | Period    | Source           | Best Modality
    ──────────────────────────────────────────────────────────────
    Cardiac cycle  | ~1 s      | Heart            | Quantum
    Respiratory    | ~4 s      | Lungs            | RF + Quantum
    Movement       | ~0.1-10 s | Whole body       | RF
    Circadian      | ~24 h     | All systems      | RF + Quantum
    Seasonal       | ~90 d     | Metabolic        | Long-term graph

    RuVector stores multi-scale graph evolution:
    - Fast buffer: 1-second coherence snapshots (cardiac)
    - Medium buffer: 30-second windows (respiratory)
    - Slow buffer: hourly graph summaries (circadian)
    - Archive: daily/weekly baselines (longitudinal)
```

---

## 10. Room-Scale Ambient Health Monitoring

### 10.1 The Ambient Health Room

```
Ambient Health Monitoring Room:

    Ceiling:
    ┌─────────────────────────────────────┐
    │  E───E───E───E───E                  │  E = ESP32 (16 nodes)
    │  │               │                  │  Q = NV Diamond (4 nodes)
    │  E   Q       Q   E                  │
    │  │               │                  │  No wearables required
    │  E       ☺       E    ← Person      │  No cameras
    │  │               │                  │  Privacy preserving
    │  E   Q       Q   E                  │
    │  │               │                  │
    │  E───E───E───E───E                  │
    └─────────────────────────────────────┘

    Continuous output:
    - Heart rate: ±2 BPM (quantum-enhanced)
    - Breathing rate: ±1 BPM (RF-based)
    - Movement class: sitting/standing/walking/lying
    - Activity level: sedentary/moderate/active
    - Sleep stage: awake/light/deep/REM (long-term learning)
    - Fall detection: <2 second alert
    - Cardiac anomaly: arrhythmia flag
```

### 10.2 Use Case: Elderly Care

```
Elderly Care Application:

    Morning routine monitoring:
    ┌────────────────────────────────────────┐
    │ 06:00 - Lying in bed, normal breathing │  RF: low movement
    │ 06:15 - Movement detected, getting up  │  RF: topology shift
    │ 06:16 - Standing, walking to bathroom  │  RF: boundary tracks
    │ 06:20 - Seated (bathroom)              │  RF: stable partition
    │ 06:25 - Walking to kitchen             │  RF: boundary moves
    │ 06:30 - Standing (kitchen activity)    │  RF: stable + motion
    │ ...                                    │
    │ 07:00 - Seated (eating)                │  RF: stable
    └────────────────────────────────────────┘

    Alert conditions:
    ⚠️ No movement for > 2 hours (unusual for time of day)
    ⚠️ Fall signature (rapid topology change + stillness)
    ⚠️ Cardiac irregularity (quantum: irregular R-R intervals)
    ⚠️ Breathing abnormality (RF + quantum: apnea pattern)
    ⚠️ Deviation from learned daily pattern (graph baseline)

    Long-term trends:
    📊 Mobility declining over weeks (movement graph metrics)
    📊 Sleep quality changes (nighttime coherence patterns)
    📊 Cardiac health trends (HRV from quantum sensors)
```

### 10.3 Hospital Room Application

```
Hospital Patient Monitoring Without Wires:

    Current:                        Proposed:
    ┌────────────────┐             ┌────────────────┐
    │ Patient with:  │             │ Patient:       │
    │ - ECG leads    │             │ - No wires     │
    │ - SpO2 clip    │             │ - Free movement│
    │ - BP cuff      │             │ - Better sleep │
    │ - Resp belt    │             │ - Less infection│
    │                │             │                │
    │ 12 wire leads  │             │ Ambient sensors│
    │ Skin irritation│             │ Continuous data│
    │ Movement limit │             │ + mobility data│
    └────────────────┘             └────────────────┘

    Ambient system provides:
    ✅ Heart rate (quantum: comparable to ECG for rate)
    ✅ Respiratory rate (RF: ±1 BPM)
    ✅ Movement/activity (RF: excellent)
    ✅ Fall detection (RF: <2s)
    ⚠️ Heart rhythm detail (quantum: approaching clinical)
    ❌ SpO2 (requires optical — not yet ambient)
    ❌ Blood pressure (requires contact measurement)
```

---

## 11. Graph-Based Biomedical Analysis

### 11.1 Minimum Cut for Physiological Boundary Detection

```
Physiological Mincut Applications:

    Application 1: Cardiac Conduction Mapping
    ─────────────────────────────────────────
    36 quantum sensors over chest
    Coherence graph at cardiac frequency (1-2 Hz)
    Mincut reveals: conduction pathway boundaries
    Clinical use: Identify accessory pathways (WPW syndrome)
                  Guide ablation targeting

    Application 2: Muscle Compartment Sensing
    ─────────────────────────────────────────
    64 sensors over limb
    Coherence in motor frequency band (20-200 Hz)
    Mincut reveals: boundaries between muscle groups
    Clinical use: Compartment syndrome early detection
                  Muscle activation pattern analysis

    Application 3: Neural Functional Boundaries
    ─────────────────────────────────────────
    128 sensors over scalp
    Coherence in multiple frequency bands
    Mincut reveals: functional network boundaries
    Clinical use: Pre-surgical mapping (avoid eloquent cortex)
                  Track rehabilitation progress
```

### 11.2 Temporal Health State Evolution

```
Health State as Graph Evolution:

    Day 1:                      Day 30:
    ┌─────────────┐            ┌─────────────┐
    │ ●━━━●━━━●   │            │ ●━━━●───●   │
    │ ┃       ┃   │            │ ┃       │   │
    │ ●━━━●━━━●   │            │ ●━━━●───●   │
    │ (healthy)   │            │ (degrading)  │
    └─────────────┘            └─────────────┘
    Cut value: 0.95             Cut value: 0.72

    ━━━ = high coherence edge
    ─── = weakening edge

    RuVector stores:
    - Daily graph snapshots
    - Weekly aggregate metrics
    - Trend analysis (Welford statistics)
    - Anomaly detection (Z-score on cut value)

    Alert: Cut value dropped 24% over 30 days
    → Investigate cardiac/respiratory function
```

### 11.3 Population-Level Graph Baselines

```
Population Health Baselines:

    Collect biomagnetic graphs from N subjects:
    - Age-stratified baselines
    - Gender-adjusted norms
    - Activity-level normalized

    Per-demographic baseline:
    G_baseline(age, gender) = mean graph over cohort

    Individual deviation score:
    d(G_patient) = graph_distance(G_patient, G_baseline)

    Graph distance metrics:
    - Cut value ratio: λ_patient / λ_baseline
    - Spectral distance: ||eigenvalues_p - eigenvalues_b||
    - Edit distance: minimum edge weight changes
    - Fiedler ratio: λ₂_patient / λ₂_baseline

    Screening threshold:
    d > 2σ → flag for follow-up
    d > 3σ → urgent evaluation
```

---

## 12. Integration Architecture

### 12.1 Mapping to Existing Crates

```
Crate Integration for Biomedical Sensing:

    wifi-densepose-signal/ruvsense/
    ├── coherence.rs      → Extend for biomagnetic coherence
    ├── coherence_gate.rs → Adapt thresholds for physiological signals
    ├── longitudinal.rs   → Health trend tracking (Welford stats)
    ├── field_model.rs    → Extend SVD model for body field
    └── intention.rs      → Pre-event prediction (seizure, cardiac)

    wifi-densepose-ruvector/viewpoint/
    ├── attention.rs      → Cross-modal attention (RF + quantum)
    ├── coherence.rs      → Phase coherence for biomagnetic
    ├── geometry.rs       → Sensor placement optimization (QFI)
    └── fusion.rs         → Multimodal sensor fusion

    wifi-densepose-vitals/ (NEW EXTENSION)
    ├── cardiac.rs        → Heart rhythm from quantum sensors
    ├── respiratory.rs    → Breathing from RF + quantum
    ├── neural.rs         → Brain coherence analysis
    ├── vascular.rs       → Circulation sensing
    └── diagnostic.rs     → Coherence-based diagnostic output
```

### 12.2 Data Pipeline

```
Biomedical Sensing Pipeline:

    ┌──────────┐     ┌──────────┐     ┌──────────┐
    │ Quantum  │────→│ Feature  │────→│ Coherence│
    │ Sensors  │     │ Extract  │     │ Graph    │
    └──────────┘     └──────────┘     └────┬─────┘
                                           │
    ┌──────────┐     ┌──────────┐          │
    │ ESP32    │────→│ CSI Edge │──────────→┤
    │ Mesh     │     │ Weights  │          │
    └──────────┘     └──────────┘          │
                                           ▼
                                    ┌──────────┐
                                    │ Multimodal│
                                    │ Graph     │
                                    │ Fusion    │
                                    └────┬─────┘
                                         │
                          ┌──────────────┼──────────────┐
                          ▼              ▼              ▼
                    ┌──────────┐  ┌──────────┐  ┌──────────┐
                    │ Mincut   │  │ Spectral │  │ Temporal │
                    │ Analysis │  │ Analysis │  │ Tracking │
                    └────┬─────┘  └────┬─────┘  └────┬─────┘
                         │             │             │
                         └──────┬──────┘─────────────┘
                                ▼
                         ┌──────────┐
                         │Diagnostic│
                         │ Report   │
                         └──────────┘
```

### 12.3 ADR-045 Draft: Quantum Biomedical Sensing Extension

```
# ADR-045: Quantum Biomedical Sensing Extension

## Status
Proposed

## Context
The RF topological sensing architecture (ADR-044) provides room-scale
detection via ESP32 WiFi mesh and minimum cut analysis. Quantum sensors
(NV diamond, OPMs) operating at pT-fT sensitivity can extend this to
biomedical monitoring by detecting organ-level electromagnetic fields.

The existing crate architecture (signal, ruvector, vitals) provides
foundations for biomagnetic signal processing and temporal tracking.

## Decision
Extend the sensing architecture with quantum biomedical capabilities:

1. Add quantum sensor integration to wifi-densepose-vitals
2. Implement biomagnetic coherence graph construction
3. Extend minimum cut analysis for physiological boundaries
4. Add coherence-based diagnostic framework
5. Build multimodal fusion (RF + quantum + acoustic)

## Consequences

### Positive
- Enables non-contact vital sign monitoring
- Opens clinical diagnostic applications
- Leverages existing graph analysis infrastructure
- Privacy-preserving by design (no imaging)

### Negative
- Quantum sensors add significant hardware cost
- Requires magnetic shielding for clinical-grade sensing
- Regulatory approval pathway is undefined
- Clinical validation requires extensive trials

### Neutral
- Compatible with classical-only deployment
- Quantum features are additive (graceful degradation)
- Same graph algorithms work for both RF and biomagnetic data
```

---

## 13. From Anatomy to Field Dynamics

### 13.1 The Paradigm Shift

```
Medical Imaging Evolution:

    1895: X-Ray          → See bone density
    1972: CT Scan         → See tissue density in 3D
    1977: MRI             → See tissue composition
    1950s: Ultrasound     → See tissue boundaries in motion
    1990s: fMRI           → See blood flow changes
    2020s: Quantum Sensing → See electromagnetic dynamics

    The progression:
    Structure → Composition → Flow → Function → Physics

    Quantum biomedical sensing completes the arc:
    From observing what the body IS
    To observing what the body DOES
    At the level of electromagnetic physics
```

### 13.2 Diagnosis as Field Dynamics Monitoring

```
Traditional Diagnosis:              Field-Dynamic Diagnosis:
────────────────────               ─────────────────────────
"What does the image show?"        "How has the field topology changed?"
Point-in-time snapshot             Continuous temporal monitoring
Anatomical abnormality             Functional coherence breakdown
Requires hospital visit            Ambient monitoring at home
Expert interpretation              Automated graph analysis
Late detection (structural)        Early detection (functional)
Binary (normal/abnormal)           Continuous health score
```

### 13.3 Vision: The Electromagnetic Body

The long-term vision is a complete real-time map of the body's electromagnetic dynamics:

```
The Electromagnetic Body Model:

    Not anatomy → but field topology
    Not position → but coherence boundaries
    Not images  → but graph evolution
    Not snapshots → but continuous streams
    Not expert reading → but algorithmic detection
    Not hospital → but ambient

    Every organ is a source node in the physiological graph
    Every coherence link is an edge
    Every disease is a topological change
    Every recovery is a coherence restoration

    The minimum cut is the diagnostic signal:
    Where does the body's electromagnetic coordination break?
```

### 13.4 Research Roadmap

```
Timeline:

    2026-2027: RF Topological Sensing (classical)
    ├── ESP32 mesh deployment
    ├── Room-scale presence and movement
    └── Breathing detection via RF

    2027-2029: Quantum-Enhanced Room Sensing
    ├── NV diamond nodes for cardiac detection
    ├── Hybrid RF + quantum graph
    └── Non-contact vital signs at 1m

    2029-2031: Biomagnetic Coherence Diagnostics
    ├── 64+ quantum sensor array
    ├── Coherence-based health scoring
    └── Clinical validation studies

    2031-2033: Neural Field Imaging
    ├── Wearable OPM for brain monitoring
    ├── Non-invasive BCI
    └── Closed-loop neural stimulation

    2033-2035: Full Physiological Observatory
    ├── 256+ multimodal sensors
    ├── Cellular-level EM detection
    └── Population health baselines

    2035+: Quantum-Native Medicine
    ├── Chip-scale quantum sensors
    ├── Ambient health monitoring standard
    └── Electromagnetic medicine as discipline
```

---

## 14. References

1. Boto, E., et al. (2018). "Moving magnetoencephalography towards real-world applications with a wearable system." Nature 555, 657-661.
2. Brookes, M.J., et al. (2022). "Magnetoencephalography with optically pumped magnetometers (OPM-MEG): the next generation of functional neuroimaging." Trends in Neurosciences 45, 621-634.
3. Jensen, K., et al. (2018). "Non-invasive detection of animal nerve impulses with an atomic magnetometer operating near quantum limited sensitivity." Scientific Reports 8, 8025.
4. Alem, O., et al. (2023). "Magnetic field imaging with nitrogen-vacancy ensembles." Nature Reviews Physics 5, 703-722.
5. Tierney, T.M., et al. (2019). "Optically pumped magnetometers: From quantum origins to multi-channel magnetoencephalography." NeuroImage 199, 598-608.
6. Bison, G., et al. (2009). "A room temperature 19-channel magnetic field mapping device for cardiac signals." Applied Physics Letters 95, 173701.
7. Zhao, M., et al. (2006). "Electrical signals control wound healing through phosphatidylinositol-3-OH kinase-γ and PTEN." Nature 442, 457-460.
8. McCraty, R. (2017). "New frontiers in heart rate variability and social coherence research." Frontiers in Public Health 5, 267.
9. Baillet, S. (2017). "Magnetoencephalography for brain electrophysiology and imaging." Nature Neuroscience 20, 327-339.
10. Hill, R.M., et al. (2020). "Multi-channel whole-head OPM-MEG: Helmet design and a comparison with a conventional system." NeuroImage 219, 116995.

---

## 15. Summary

Quantum biomedical sensing represents the convergence of three advancing frontiers:

1. **Quantum sensor technology** — Room-temperature sensors approaching fT sensitivity
2. **Graph-based analysis** — Minimum cut and coherence topology for health monitoring
3. **Ambient computing** — Non-contact, privacy-preserving, continuous measurement

The key insight is that **disease is a topological change in the body's electromagnetic
coherence graph**. The same minimum cut algorithms that detect a person walking through
an RF field can detect when physiological systems fall out of synchronization.

This creates a unified architecture from room sensing to clinical diagnostics:
- Same graph theory (minimum cut, spectral analysis)
- Same temporal tracking (RuVector, Welford statistics)
- Same attention mechanisms (cross-modal, cross-scale)
- Same infrastructure (Rust crates, ESP32 + quantum nodes)

The body becomes a signal graph. Health becomes coherence. Diagnosis becomes
detecting where the topology breaks.
