Early 1990's vehicles saw the first silicon accelerometer for an airbag crash sensor application. These devices have obtained extensive coverage in the popular and trade press. However, with the exception of these two applications, vehicle design engineers have not opted to include MEMS devices into their systems.. The next five-to-seven years will provide significant opportunities MEMS devices - whether it be in entirely new applications or in the replacement of traditional technologies. This movement is being fueled by the following factors:
In addition, automotive components must be able to be produced in extremely large volumes, typically one million or more units per year. This is necessary not only from a vehicle demand point of view, but from the necessity to recoup the large investment' associated with fixed design and manufacturing costs. Operating lifetimes of up to 10 years/150,000 miles. and very low unit prices are also required; Essentially, we can consider automotive components to require the ruggedness of military parts with the price of consumer products. These qualities are inherent in MEMS.
Component cost is a significant factor in the selection criteria of automotive System designers. The total cost of a sensor/actuator frequently includes. the MEMS device, signal conditioning electronics (e.g., temperature compensation, filtering, amplification), package, connector/cable harness, and testing.
As a result. the cost of the MEMS device itself constitutes a minority of the total delivered component cost. Therefore, a significant challenge to achieve highly efficient design for manufacturability is imposed on all suppliers who wish to be successful in the automotive sector.
With the advent of microprocessor compatibility imposed on many automotive sensor/actuator applications, silicon is uniquely qualified to provide high levels of monolithic vertical functional integration using .popular semiconductor and classical micromachining processing.
Application |
Sensor Structure |
Status |
MEMs Opportunity |
| Antilock Braking/Vehicle Dynamics/Suspension | Steering Position/ Wheel Rotation |
Production |
Low |
| Suspension | Pressure |
Ltd. Production |
Med |
| " | Valve |
Future |
Low |
| " | Acceleration |
Ltd Production |
High |
| " | Rate |
Ltd Production |
High |
| " | Displacement |
Ltd Production |
Low |
| Airbag | Acceleration |
Production |
High |
| Actuation | Frontal Impact Pressure (Canister) |
Future |
High |
| " | Displacement Side-Impact |
Ltd. Production |
Low |
| " | Pressure |
Future |
Med. |
| " | Acceleration (side Impact) |
Ltd. Production |
High |
| Seat Occupancy | Presence/ |
Ltd. Production |
Low |
| " | Force Displacement |
Ltd. Production |
Low |
| Object Avoidance | Presence/ |
Ltd. Production | Low |
| " | Displacement |
Future |
|
| Navigation | Yaw Rate/Gyro |
Ltd. Production |
High |
| Navigation | Wheel Rotation |
Limited Production |
Low |
|
|
|
Source: Roger Grace Associates
Applications |
Function |
Status |
MEMS Opportunity |
| Digital Engine Control: | |||
| Fuel | Level |
Production |
Low |
| Cylinder | Pressure |
Future |
Low |
| Manifold (MAP) | Pressure |
Production |
High |
| Barometric | Pressure |
Production |
High |
| Engine Knock | Vibration |
Ltd. Production |
Low |
| Mass Airflow | Flow |
Production |
Med |
| Exhaust | Gas Analysis | Production | Low |
| Crankshaft | Position | Major Production | Low |
| Camshaft | Position | Ltd. Production | Low |
| Throttle | Position | Ltd. Production | Low |
| EGR | Pressure | Production | High |
| Fuel Pump | Pressure | Ltd. Production | High |
| Continuously Variable Transmission: | |||
| Temperature | Future | Low | |
| Pressure | Future | High | |
| Microvalve | Future | Low | |
| Fuel | Pressure | Ltd. Production | High |
| Injection | Nozzle | Ltd. Production | High |
| Diesel Turbo Boost | Pressure | Ltd. production | High |
Source: Roger Grace Associates
Application |
Function |
Status |
MEMs Opportunity |
| Seat | Presence |
Ltd. Production |
Low |
| Seat Control | Valve |
Future |
Med |
| " | Displacement |
Future |
Low |
| Climate | Mass Air flow |
Future |
Med |
| " | Temperature |
Production |
Low |
| " | Humidity |
Future |
Low |
| " | Air Quality |
Future |
High |
| Compressor | Pressure |
Production |
High |
| Compressor Control | Temperature |
Production |
Low |
| Security | Proximity |
Ltd. Production |
Low |
| " | Motion |
Ltd. Production |
Low |
| " | Vibration |
Ltd. Production |
Low |
| " | Displacement |
Ltd. Production |
Low |
| " | Keyless Entry |
Ltd. Production |
Low |
Source. Roger Grace Associates
| Application | Function | Status | MEMS Opportunity |
| Coolant | Temperature | Production | Low |
| " | Quality | Future | High |
| System | Level | Ltd. Production | Low |
| Tire Pressure | Pressure | Ltd. Production | High |
| Engine Oil | Pressure | Production | High |
| " | Level | Production | Low |
| " | " | Future | Med |
| " | Quality | Future | Med |
| Brake | Pressure | Ltd. Production | High |
| Brake System | Level | Future | Low |
| Transmission Fluid | Pressure | Ltd. Production | High |
| " | Level | Future | Low |
| " | Quality | Future | Med |
| Fuel | Pressure | Future | High |
| Fuel System | Level | Future | Low |
| " | Pressure (EVAP) | Ltd. Production | High |
| Vehicle Speed | Velocity | Production | Low |
Source: Roger Grace Associates