Too little information.  What kind of sensor is it?  How will it be used?

What is the market?  Have you discussed requirements with potential users?  Are there existing packaging, performance and environmental standards you can consult?

What are the environmental constraints?  Do you need to protect the sensor from humidity?  Is hermetic encapsulation desirable or even essential?  Are there any problems with repeated heat/cold/humidity cycles?

What are the interfacing requirements?  Are there electrical connections?  Do you use a demountable socket?  For a flying lead, either electrical or optical fiber cable, what tensile and bending stresses must it survive.  Do you specify a number of fatigue loading cycles and a minimum bend radius.  Should the cable be protected by a strain relief boot where it enters the package?

Will the sensor be mounted on a circuit board?  Is there a standard pin-out or pad spacing you must comply with?  Is it compatible with lead-free solder?  Will it survive the temperature changes associated with soldering - either by hand or with re-flow soldering.  Will it survive re-working with a heat gun?

Does it require electrical screening?

Are there competing devices on offer whose specifications you can compare?

Can you partner with someone with experience in device packaging?

If you don't know where to start, I suggest you open up discussions with potential users who can identify which requirements are essential and others which may be desirable. 

I think there is a lack of information so that you get a useful answer. What is the sensor type? Applications that want to use it where?

this Metal Oxide based optical sensor like that UV sensor, i want use it in wet and hot environment.