Sensors

Fundamentals
Acoustic
Space
Biosignals
Next
1. Start Experimenting
2. More Ressources

Note:

This page contains some reminders, but assumes you already participated in HTMAA, otherwise, don’t miss the excellent page about Input Devices. It is also difficult to cover everything that was in the 2018 Metrology session and it’s absolutely worth it.

Fundamentals

Resistance

Potentiometer (can measure rotation, or position if linear)
Force Sensitive Resistor (FSR) => Piezoresistivity (Piezo: from Ancient Greek πιέζω, “to press”).
Bonus: DIY approach with chemical functionalization:

Capacitance

The classics (1/2): MCU approach: (credit: Arduino)
The classics (2/2): 12 more pins with the NXP MPR121
Mutual Capacitance Matrix: MuCa: (open hard+software)
3d sensing: Microchip GestIC series (credit: Microchip)
High Accuracy (up to 28bits) “Capacitance-Digital Converter”: TI FDC2214
- demo of its “noise-immunity”
- github repo for dev board use with python (great for interstitial capacitance measurement)

Note: these examples focused on touch/finger sensing, but these sensors can measure much more (water level, shape distortion, etc).

Inductance

High Accuracy (up to 28bits) “Inductance-Digital Converter”: TI LDC1614
- github repo for dev board use with python + demo: Bonus: visualization of resonant frequency with remote resistance measurement.
- Research Application example

Acoustic

Types of Microphones: (credit: Grace Noel - Fiber@MIT)
MEMS mic: (credit: Coventor)
Bonus: MEMS mic jamming:

(credit: uChicago)

Bonus: custom speaker => custom mic:

Space

Distance

Sonar
- Principle:
(credit: Trion Projects)
- MEMS transducer:
(credit: Semiconductor Store)

Radar
- Principle: (more)
(credit: The Signal Path)
- Google Soli:
- Texas Instruments’ AWR6843AOP (dev. board)
Optical
- Sharp Familly:
- ST Familly (wider Field of View):
(credit: Pololu)
- APDS9960 multifunction: Proximity, Light, RGB, and Gesture Sensor!
(credit: ProtoSupplies)
- Depth sensor list - From the Kinect to the iPhone:

(credit: Microsoft, Apple)

3d Positioning

Lasers: Hivetracker
Magnetic:
- Polhemus Fastrak (example project)
- Razer Hydra

(credit: Razer, howiem.com)

Open Alternative: Plume (+dev logs)
RSSI & TDOA in UWB (6 GHz): DecaWave DWM1000

(credit: Adafruit)

Differential GPS (high-accuracy GPS): Example with Swift Navigation

(credit: Swift Navigation)

Inertial Measurement Units

IMU Basics:
- Accelerometer: it gives linear accelerations (and gravity vector)
- Gyroscope: it gives angular rate, it’s great for dynamic measures but it needs integration for orientation estimation and it creates drift (noise is accumulated)
- Magnetometer: it is slow but it doesn’t drift
More
Sensor Fusion illustration

(credit: codeproject.com)

The most practical IC: BNO055 (with embedded sensor fusion)
Wireless IMU boards:
DIY: Optical Accelerometer!?

Biosignals

Start Experimenting

You can get a basic sensor kit for $10 or less:

(credit: Aliexpress)

Looking for a part?

The octopart comparator will usually find some of the cheapest in the fast providers
AliExpress will probably be cheaper, but usually slower
If you work with a Chinese manufacturer, TaoBao might be better (but not practical to send outside of China)