Smart, web enabled fridge Marty Lewis

Basic I/O INPUTS Weight/size Sensor Barcode Reader Touch Pad / Touchscreen LCD OUTPUTS SVGA LCD INPUT AND OUTPUT Internet connectivity interface Ethernet, USB, g, Bluetooth, Modem

Weight Sensor Options Load Cell / Strain Gauge Each load cell is comprised of a durable material with one or more strain gauges attached to or embedded in it. A strain gauge consists of a wire (or wires) that transmits a mild electric current. As the cell is subjected to weight, the wire in the strain gauge is altered or compressed slightly. The change in the wire results in a difference in the resistance to the current passing through it. Piezoelectric Piezoelectric sensors are embedded in a conducting material. When weight is applied, the pressure changes the voltage of the electrical charge flowing through the conductor. The sensors measure the change in voltage and calculate the load. The amounts from each sensor are added together. Capacitive Capacitance is a measure of the electrical charge stored between two electrodes separated by an air gap. As the electrodes are moved closer to or farther from one another, the air gap changes, and therefore so does the capacitance

Circuit Board Mounted Load Cell Capacities: 25 pounds-force Rated Output: 2 mV/V nominal Zero Offset:  0.4 mV/V Overload, safe: 150% RO Overload, ultimate: 200% RO Excitation recommended: 5 to 15 Vdc Bridge Resistance: 5,000  5% Bridge Configuration: 4-Wire closed bridge Insulation Resistance: >1000 M 50 Vdc Operating Temp. Range: -20  C to +125  C Calibrated Temp Range: -20  C to +100  C Temperature Effect on Zero Balance:  0.1% /  C (  0.06% /  F) Temperature Effect on Span: +0.05% reading/  C (0.03%/  F) Long Term Stability: <0.1% RO per year Nonlinearity:  0.5% RO Hysteresis:  0.2% RO Nonrepeatability: <0.2% RO Electrical Termination: 0.040” dia. Gold pins on 0.2” pitch

Piezoelectric sensor Most piezoelectric sensors weight sensors are for large weigh in motion systems. Could not find a good supplier / specs for a piezoelectric weight sensor.

I-Scan force/pressure sensor Have many shapes and sizes. Can also have custom sizes made. Can choose a sensel density for your specific need

Flexi Force Variable Force sensing 0 – 1 lb 0 – 25 lb 0 – 100 lb Custom Length 2” to 8”

Barcode reader options Contact vs non-contact Contact Wand Non-Contact CCD Laser Projection (Omni-directional Laser) Decoded vs non-decoded Decoded Decode done by hardware in the scanner device Non-decoded Cheaper, can be done externally in hardware or software

MS 861i projection scanner

Cue: cat barcode scanner Free barcode scanner given out at Radioshack Can be modified to read regular barcodes Many websites offer drivers and documentation on how to unlock its capabilities

External Interface Connection to the online grocers / database: USB / Wireless USB a/b/g Bluetooth Wired ethernet port Modem

Connectivity Comparison

Allowance for multiple connectivity hardware Remove dependence on a specific hardware internet interface Keep the communication level at the TCP/IP stack Allow any hardware interface to communicate via the TCP/IP stack