a Cubic-Millimeter Computer

canolaokahumpkaElectronics - Devices

Nov 2, 2013 (4 years and 8 months ago)


Smart Dust: Communicating with
a Cubic
Millimeter Computer

Presentation by

Hörður Mar Tómasson

13. October 2006

The Smart Dust project

Went on at UC Berkeley 1998

Primary investigator: Kristofer S.J. Pister

The goal

1 mm
³ motes

with onboard sensors,


and wireless communications facilities

forming the basis of a sensor network

Fundamental goal

To explore the limitations of
microfabrication technology

Ideas for uses for smart dust

Surveillance networks for defense

Monitoring environmental conditions

computer interfaces

Inventory and product quality control

Tracking movements of animals

Power considerations

Batteries: 1 J/mm


Capacitors: 10 mJ/mm

usable storage

Solar cells: 1 J/(mm
² ∙ day) in sunlight or

10 mJ
² ∙ day) indoors

Optical receiver: 0.1 nJ/bit

Optical transmitter: 1 nJ/bit

A/D converter: 1 nJ/sample

Computation: 1 pJ/instruction

Power considerations

1000 8
bit operations per sample will not
make a big difference in power used.

1 mJ per day from a solar cell indoors will
be sufficient for making a measurement
every second, processing the result and
transmitting it.

energy computation

Smaller transistors with less parasitic capacitance
consume less dynamic power.

Reduced supply voltage also means less dynamic

Leakage currents can be decreased by reverse
biasing the channel
source junction.

Clock rates of 1
100 kHz are sufficient for
working with some important types of physical

Wireless communication

Radio communication currently requires
several mW of power and preferably
antennas longer than a millimeter.

Semiconductor lasers and diode receivers
can use less power and are more directional.

The Smart Dust project explored optical

Passive reflective systems

A MEMS corner cube reflector (CCR) with
a side that can be tilted

Less than 1 nJ used per transition

The mote can use the CCR to communicate
with a base station equipped with a light

Active steered laser systems

Semiconductor laser

Collimating lens

MEMS steerable

Optical receiver

An imaging receiver has several benefits.

Only one pixel receives the signal but the
ambient light is divided between the pixels.

Several signals can be received in parallel.

The authors did an experiment with a laser
and a video camera.

A smart pixel has an integrated receiver.

Ad hoc mote networks

If the motes can communicate directly with
each other, they can form ad hoc multihop
networks to carry the data around.

This is an interesting problem for network
algorithm design.

An Ultra
Low Energy
Microcontroller for Smart Dust
Wireless Sensor Networks

Presentation by

Hörður Mar Tómasson

13. October 2006

Creators of the microcontroller

Brett A. Warneke

Kristofer S.J. Pister


The microcontroller
was developed for this
prototype smart dust

Architectural features

Highly independent subsystems

level clock gating in decoder

Processor halt mode

Guarded ALU inputs

Multiple busses

Harvard architecture

store RISC

Main oscillator

Runs continuously at a few kHz

Operates real time clock and five timers

One timer for each sensor sampling period

One timer for invoking the transmitter

One timer for invoking the receiver

One timer for waking up the datapath

Other oscillators

100 kHz for driving the sensor ADC

8 MHz for sampling a 1 Mb/s optical signal

ADC automation

The ADC is configurable to different levels
of automation.

At the minimum level, the sensor and
sample and hold are activated.

At the maximum level, the voltage is
compared to a threshold and, if the
threshold is exceeded, converted and stored
in the SRAM along with a time stamp.


The processor core uses two registers to
specify what memory blocks contain data to
be transmitted.

The transmitter formats the data into
packets and transmits them asynchronously
to the CCR.

Four types of received packets

Short sync packets trigger the transmitter.

Immidiate packets contain an instruction
that is immediately executed.

Program packets are streamed to the
program memory.

Data packets are streamed to the data

Trimmable oscillator


RF Telemetry System for an
Implantable Bio
MEMS Sensor

Presentation by

Hörður Mar Tómasson

13. October 2006

The long range goal

NASA wants to develop implantable
sensors to monitor physiological parameters
of humans during space flights.

It would be of great benefit to have
contactless powering and data readout for
the implants.

Advantages of contactless powering
and telemetry

The inductor/antenna is small in size.

There is no need to implant batteries.

The circuit only operates when interrogated,
avoiding heating of the surrounding tissue
and extending the life span of the sensor.

through wires not needed, enhancing
mobility and reducing risk of infection.

This paper

A system for contactless powering and RF
telemetry from an implantable bio

A square spiral inductor/antenna

A MEMS capacitive pressure sensor

A pick
up antenna

Spiral inductor/antenna

MEMS pressure sensor

up system

A printed circuit with mounted components

Spiral inductor/antenna, printed

MMIC low noise amplifier, mounted on

Antenna matching network, mounted
discrete components,

Output connector

Operating principle

The idea is to send pulses down into the
implant and detect the decaying sine


Desired frequency range: 200

700 MHz

Expected capacitance of pressure sensor:

4 pF

Expected required parameters for square
inductor: 150 nH and Q=10

Several inductors with different geometries
were tried.

Fabrication of the inductor

High resistance silicon wafer

on glass coating

Chrome/gold metallization

The goal is to have high Q.

The next step

Exploring coupling between the inductor
and the pick
up antenna through stratified