Performance Specifications
How Piezoresistive Sensing Works
Haptica Skin is a grid-based tactile sensor. Its sensing surface consists of conductive rows and columns whose intersection points form individual sensing locations called taxels (tactile pixels). Each taxel is separated by a piezoresistive material—a substance that changes its electrical resistance in response to applied force.
When pressure is applied to any point on the sensor surface, the resistance at that intersection decreases proportionally. By rapidly scanning each row and column, the Axon V1 microcontroller records the force level at every taxel, capturing the timing, magnitude, and spatial distribution of contact across the entire sensing area at 120 Hz.
The result is a real-time pressure map output as calibrated force vectors in Newtons or pressure in MPa.
Key Specifications
| Parameter | Value | Notes |
|---|---|---|
| Pressure Range (Calibrated) | 1.0 ~ 6.0 bar | 1.02 - 6.12 kgf/cm² |
| Pressure Range (Capable) | 0.39 ~ 29.42 bar | 0.40 - 30.00 kgf/cm² |
| Spatial Resolution | 5mm (2-axis) / 10mm (3-axis) | Center-to-center spacing |
| Array Size | 16x10 or 32x32 | Custom sizes available |
| Refresh Rate | 120 Hz | — |
| Operating Temperature | 25°C - 85°C | Optional temp compensation |
| Durability | > 1,000,000 cycles | Preliminary testing |
| Elasticity | ~15% | Without trace damage |
Electrical & Interface
- Interface: USB Full Speed (12 Mbps)
- Connector: USB-C (USB-A compatible)
- Power Consumption: ~250 mA @ 5V
- Microcontroller: STM32-based Axon V1
- Driver Support: Windows, Linux, macOS (Drivers provided)
- Multi-Device: Supports up to 8 skins per machine
Data Output
The Axon V1 controller outputs a standardized tensor of tactile data.
- Format: 2-axis or 3-axis force vectors.
- Units: Calibrated Newtons (N) or Pressure (MPa).
- Timestamp: Microsecond-precision hardware timestamp for synchronization.
We provide full characterization data for every sensor batch, so you don't have to perform your own calibration.
Sensor Uniformity
A sensor's uniformity determines its ability to produce accurate and repeatable measurements. For a grid-based sensor, two properties matter:
- Cell Repeatability — Does the same taxel give the same reading under the same force?
- Cell-to-Cell Uniformity — Do different taxels respond identically to identical loads?
Haptica Skin achieves high uniformity through precision manufacturing of our proprietary piezoresistive compound. However, minor variations between taxels are inevitable in any production process. This is why every Haptica sensor ships with factory calibration data—a per-taxel compensation map that normalizes response curves across the entire array.
The Axon V1 applies this calibration automatically, linearizing the raw resistance data into calibrated force output. You receive production-ready data without performing your own characterization.
Spatial Resolution
A grid sensor's spatial resolution determines:
- The smallest contact area that can be reliably detected
- The positional accuracy of contact localization
Haptica Skin offers 5mm center-to-center spacing for 2-axis sensing and 10mm spacing for 3-axis configurations. Standard array sizes include 16×10 (160 taxels) and 32×32 (1,024 taxels), with custom geometries available.
The Trade-off: Every grid-based sensor has inherent "dead space"—the insensitive gaps between taxels. Higher taxel density reduces dead space and improves minimum detectable contact size, but increases manufacturing complexity and data throughput requirements.
For robotic manipulation, our 5mm resolution captures the contact patterns relevant to grasp stability and slip detection. Applications with broader load distributions (seat pressure, industrial surfaces) may use lower-density configurations optimized for cost and simplicity.
| Resolution | Best For |
|---|---|
| 5mm (high density) | Robotic fingers, precision grippers, dexterous manipulation |
| 10mm (standard) | Palms, industrial grippers, broad contact surfaces |
| Custom | Application-specific geometries |
Durability & Form Factor
Sensor durability, thickness, and signal integrity are interconnected:
- Thicker sensors are more mechanically robust but introduce crosstalk—where a point load deforms adjacent taxels that aren't actually being loaded
- Thinner sensors minimize crosstalk but may have reduced cycle life
- Protective layers add durability but increase overall thickness
Haptica Skin is approximately 2mm thick, incorporating a TPU or silicone outer layer that protects against abrasion, chemicals, and mechanical wear. This design achieves >1,000,000 loading cycles while maintaining signal fidelity.
Our ~15% elasticity without trace damage allows the sensor to conform to curved surfaces (robotic fingertips, gripper pads) without the failure modes of rigid PCB-based alternatives.
Crosstalk Mitigation: The multi-layer construction isolates sensing elements, and our firmware applies spatial filtering to reject crosstalk artifacts in point-load scenarios.
Calibration
Unlike disposable sensors that rely on batch-level calibration assumptions, every Haptica Skin unit undergoes individual characterization:
| Calibration Type | What It Does |
|---|---|
| Per-taxel gain | Normalizes sensitivity variations across the array |
| Linearization | Converts non-linear resistance response to linear force output |
| Temperature compensation | Optional correction for thermal drift (25°C–85°C range) |
This data is stored on the Axon V1 and applied in real-time. The SDK exposes calibration APIs for advanced users who need to recalibrate after physical modifications or integrate custom compensation routines.
Calibrated Range: 1.0–6.0 bar (factory-validated accuracy) Extended Range: 0.39–29.42 bar (functional but reduced precision outside calibrated window)