Future systems will continue to become smaller and less expensive, and smart chips will be used in sensors more frequently. Self-testing options are currently available for infrared, ultrasonic, and microwave sensors. Fiber optics make it possible to transmit more signals over longer distances over a single small optic fiber. Fiber optics also provide freedom from electromagnetic and radio interference, and increased flexibility of use. Spectrum technology will become more common, permitting microwave transmissions over a large range of frequencies over telephone lines and fiber optic cables. This technology also makes jamming of signals difficult. Passive infrared systems will be improved to remove gaps between collection fingers for a solid blanket of protection, and infrared, ceiling-mounted cone protection systems will become more available. Innovations in access control systems will include improved surge protection, scrambler keypads for personal identification numbers, and the introduction of biometric techniques such as the use of voice or palm print verification. Other innovations in this area will include body skin oil, wrist-scan, and keystroke biometrics.